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Frequently asked questions: Knowledge Base

What are the main types of research design?: Quantitative research designs can be divided into two main categories:

Correlational and descriptive designs are used to investigate characteristics, averages, trends, and associations between variables.

Experimental and quasi-experimental designs are used to test causal relationships.

Qualitative research designs tend to be more flexible. Common types of qualitative design include case study, ethnography, and grounded theory designs.
Why is research design important?: A well-planned research design helps ensure that your methods match your research aims, that you collect high-quality data, and that you use the right kind of analysis to answer your questions. This allows you to draw valid, credible conclusions.
What do I need to include in my research design?: The priorities of a research design can vary depending on the field, but you usually have to specify:

Your research questions and/or hypotheses

Your overall approach (e.g. qualitative or quantitative)

The type of design you’re using (e.g. a survey, experiment, or case study)

Your sampling methods or criteria for selecting subjects

Your data collection methods (e.g. questionnaires, observations)

Your data collection procedures (e.g. operationalization, timing and data management)

Your data analysis methods (e.g. statistical tests or thematic analysis)
What is a research design?: A research design is a strategy for answering your research question. It defines your overall approach and determines how you will collect and analyze data.
How do I apply a hanging indent?: To apply a hanging indent to your reference list or Works Cited list in Word or Google Docs, follow the steps below.

Microsoft Word:

Highlight the whole list and right click to open the Paragraph options.

Under Indentation > Special, choose Hanging from the dropdown menu.

Set the indent to 0.5 inches or 1.27cm.

Google Docs:

Highlight the whole list and click on Format > Align and indent > Indentation options.

Under Special indent, choose Hanging from the dropdown menu.

Set the indent to 0.5 inches or 1.27cm.

When the hanging indent is applied, for each reference, every line except the first is indented. This helps the reader see where one entry ends and the next begins.
How should I format the Works Cited page?: According to MLA format guidelines, the Works Cited page(s) should look like this:

Running head containing your surname and the page number.

The title, Works Cited, centered and in plain text.

List of sources alphabetized by the author’s surname.

Left-aligned.

Double-spaced.

1-inch margins.

Hanging indent applied to all entries.
What goes in an MLA Works Cited list?: The MLA Works Cited lists every source that you cited in your paper. Each entry contains the author, title, and publication details of the source.
How do you administer questionnaires?: Questionnaires can be self-administered or researcher-administered.

Self-administered questionnaires can be delivered online or in paper-and-pen formats, in person or through mail. All questions are standardized so that all respondents receive the same questions with identical wording.

Researcher-administered questionnaires are interviews that take place by phone, in-person, or online between researchers and respondents. You can gain deeper insights by clarifying questions for respondents or asking follow-up questions.
How do you order a questionnaire?: You can organize the questions logically, with a clear progression from simple to complex, or randomly between respondents. A logical flow helps respondents process the questionnaire easier and quicker, but it may lead to bias. Randomization can minimize the bias from order effects.
What’s the difference between closed-ended and open-ended questions?: Closed-ended, or restricted-choice, questions offer respondents a fixed set of choices to select from. These questions are easier to answer quickly.

Open-ended or long-form questions allow respondents to answer in their own words. Because there are no restrictions on their choices, respondents can answer in ways that researchers may not have otherwise considered.
What’s the difference between questionnaires and surveys?: A questionnaire is a data collection tool or instrument, while a survey is an overarching research method that involves collecting and analyzing data from people using questionnaires.
Do I need to use full sentences in an MLA annotated bibliography?: No, MLA states that in an annotated bibliography, you can write short phrases instead of full sentences to keep your annotations concise. You can still choose to use full sentences instead, though.

Use full sentences in your annotations if your instructor requires you to, and always use full sentences in the main text of your paper.
How do I create an MLA header for a paper with multiple authors?: If you’re working on a group project and therefore need to list multiple authors for your paper, MLA recommends against including a normal header. Instead, create a separate title page.

On the title page, list each author on a separate line, followed by the other usual information from the header: Instructor, course name and number, and submission date. Then write the title halfway down the page, centered, and start the text of the paper itself on the next page.
Do I need a title page for my MLA paper?: Usually, no title page is needed in an MLA paper. A header is generally included at the top of the first page instead. The exceptions are when

Your instructor requires one, or

Your paper is a group project

In those cases, you should use a title page instead of a header, listing the same information but on a separate page.
Why doesn’t correlation imply causation?: The third variable and directionality problems are two main reasons why correlation isn’t causation.

The third variable problem means that a confounding variable affects both variables to make them seem causally related when they are not.

The directionality problem is when two variables correlate and might actually have a causal relationship, but it’s impossible to conclude which variable causes changes in the other.
What’s the difference between correlation and causation?: Correlation describes an association between variables: when one variable changes, so does the other. A correlation is a statistical indicator of the relationship between variables.

Causation means that changes in one variable brings about changes in the other; there is a cause-and-effect relationship between variables. The two variables are correlated with each other, and there’s also a causal link between them.
What’s the difference between correlational and experimental research?: Controlled experiments establish causality, whereas correlational studies only show associations between variables.

In an experimental design, you manipulate an independent variable and measure its effect on a dependent variable. Other variables are controlled so they can’t impact the results.

In a correlational design, you measure variables without manipulating any of them. You can test whether your variables change together, but you can’t be sure that one variable caused a change in another.

In general, correlational research is high in external validity while experimental research is high in internal validity.
How many variables are in a correlation?: A correlation is usually tested for two variables at a time, but you can test correlations between three or more variables.
What is a correlation coefficient?: A correlation coefficient is a single number that describes the strength and direction of the relationship between your variables.

Different types of correlation coefficients might be appropriate for your data based on their levels of measurement and distributions. The Pearson product-moment correlation coefficient (Pearson’s r) is commonly used for two quantitative variables to assess a linear relationship.
What is correlational research?: A correlational research design investigates relationships between two variables (or more) without the researcher controlling or manipulating any of them. It’s a non-experimental type of quantitative research.
What is a correlation?: A correlation reflects the strength and/or direction of the association between two or more variables.

A positive correlation means that both variables change in the same direction.

A negative correlation means that the variables change in opposite directions.

A zero correlation means there’s no relationship between the variables.
How do I cite a source with no date in MLA style?: When an online source (e.g. web page, blog post) doesn’t list a publication date, you should instead list an access date.

Unlike a publication date, this appears at the end of your MLA Works Cited entry, after the URL, e.g. “A Complete Guide to MLA Style.” Scribbr, www.scribbr.com/category/mla/. Accessed 28 Mar. 2021.

For offline sources with no publication date shown, don’t use an access date—just leave out the date.
Should I list a publication year or a full date in an MLA Works Cited entry?: The level of detail you provide in a publication date in your Works Cited list depends on the type of source and the information available. Generally, follow the lead of the source—if it gives the full date, give the full date; if it gives just the year, so should you.

Books usually list the year, whereas web pages tend to give a full date. For journal articles, give the year, month and year, or season and year, depending on what information is available. Check our citation examples if you’re unsure about a particular source type.
Should I abbreviate the names of months in MLA style?: In an MLA Works Cited list, the names of months with five or more letters are abbreviated to the first three letters, followed by a period. For example, abbreviate Feb., Mar., Apr., but not June, July.

In the main text, month names should never be abbreviated.
How are dates formatted in MLA style?: In your MLA Works Cited list, dates are always written in day-month-year order, with the month abbreviated if it’s five or more letters long, e.g. 5 Mar. 2018.

In the main text, you’re free to use either day-month-year or month-day-year order, as long as you use one or the other consistently. Don’t abbreviate months in the main text, and use numerals for dates, e.g. 5 March 2018 or March 5, 2018.
Whom should I list as the author of a dictionary entry in MLA style?: In most standard dictionaries, no author is given for either the overall dictionary or the individual entries, so no author should be listed in your MLA citations.

Instead, start your Works Cited entry and your in-text citation with the title of the entry you’re citing (i.e. the word that’s being defined), in quotation marks.

If you cite a specialist dictionary that does list an author and/or overall editor, these should be listed in the same way as they would for other citations of books or book chapters.
What do I need to include in a graduate school application?: In the US, most graduate school applications require you to include:

Transcripts from previous educational institutions

Standardized test scores (such as the GRE or MCAT)

A graduate resume

2–3 letters of recommendation

A statement of purpose

Some programs may ask you to write a personal statement in addition to, or instead of, a statement of purpose. You may also be asked to an interview.

Always carefully read the application instructions for the specific program you’re applying to.
How do I cite information from a footnote in MLA style?: Some source types, such as books and journal articles, may contain footnotes (or endnotes) with additional information. MLA style provides guidelines for referring to information from a note in an in-text citation:

To cite information from a single numbered note, write “n” after the page number, and then write the note number, e.g. (Smith 105n2)

To cite information from multiple numbered notes, write “nn” and include a range, e.g. (Smith 77nn1–2)

To cite information from an unnumbered note, write “un” after the page number, with a space in between, e.g. (Jones 250 un)
Which contributors should I mention in a Chicago film citation?: The director should always be listed in the author position in a Chicago film citation, followed by the label “director.” Other contributors to the film (actors, cinematographers, writers, composers, producers, etc.) may be listed after the film title, e.g. “Featuring Willem Dafoe and Robert Pattinson. Cinematography by Jarin Blaschke.”

Only the contributors relevant to your discussion of the film should be added. You might mention actors whose performances are discussed in detail, or the composer if the use of music in the film is examined. It’s also fine to mention no contributors other than the director, if none are relevant to your discussion.
How do I cite a source with no page numbers in Chicago style?: In Chicago style, when a source does not include page numbers but you still want to point the reader to a specific point within it, an alternative locator should be used in your note or in-text citation. With audiovisual sources (e.g. films, videos, podcasts, songs), this is a timestamp, e.g. 1:15:28.

Web pages are usually short enough that no specific locator is needed. However, for a particularly long web page, you can use a subheading from the page, in quotation marks, e.g. “Citing Sources with Notes.”

Note that page numbers should be left out of newspaper citations, even when they are available. This is because page numbers can vary between different editions of a newspaper.
What’s the difference between a lab report and a research paper?: The purpose of a lab report is to demonstrate your understanding of the scientific method with a hands-on lab experiment. Course instructors will often provide you with an experimental design and procedure. Your task is to write up how you actually performed the experiment and evaluate the outcome.

In contrast, a research paper requires you to independently develop an original argument. It involves more in-depth research and interpretation of sources and data.

A lab report is usually shorter than a research paper.
What are the sections of a lab report?: The sections of a lab report can vary between scientific fields and course requirements, but it usually contains the following:

Title: expresses the topic of your study

Abstract: summarizes your research aims, methods, results, and conclusions

Introduction: establishes the context needed to understand the topic

Method: describes the materials and procedures used in the experiment

Results: reports all descriptive and inferential statistical analyses

Discussion: interprets and evaluates results and identifies limitations

Conclusion: sums up the main findings of your experiment

References: list of all sources cited using a specific style (e.g. APA)

Appendices: contains lengthy materials, procedures, tables or figures
What is a lab report?: A lab report conveys the aim, methods, results, and conclusions of a scientific experiment. Lab reports are commonly assigned in science, technology, engineering, and mathematics (STEM) fields.
How do you avoid measurement errors?: Random error is almost always present in scientific studies, even in highly controlled settings. While you can’t eradicate it completely, you can reduce random error by taking repeated measurements, using a large sample, and controlling extraneous variables.

You can avoid systematic error through careful design of your sampling, data collection, and analysis procedures. For example, use triangulation to measure your variables using multiple methods; regularly calibrate instruments or procedures; use random sampling and random assignment; and apply masking (blinding) where possible.
Is random error or systematic error worse?: Systematic error is generally a bigger problem in research.

With random error, multiple measurements will tend to cluster around the true value. When you’re collecting data from a large sample, the errors in different directions will cancel each other out.

Systematic errors are much more problematic because they can skew your data away from the true value. This can lead you to false conclusions (Type I and II errors) about the relationship between the variables you’re studying.
What’s the difference between random and systematic error?: Random and systematic error are two types of measurement error.

Random error is a chance difference between the observed and true values of something (e.g., a researcher misreading a weighing scale records an incorrect measurement).

Systematic error is a consistent or proportional difference between the observed and true values of something (e.g., a miscalibrated scale consistently records weights as higher than they actually are).
How do you plot explanatory and response variables on a graph?: On graphs, the explanatory variable is conventionally placed on the x-axis, while the response variable is placed on the y-axis.

If you have quantitative variables, use a scatterplot or a line graph.

If your response variable is categorical, use a scatterplot or a line graph.

If your explanatory variable is categorical, use a bar graph.
How do explanatory variables differ from independent variables?: The term “explanatory variable” is sometimes preferred over “independent variable” because, in real world contexts, independent variables are often influenced by other variables. This means they aren’t totally independent.

Multiple independent variables may also be correlated with each other, so “explanatory variables” is a more appropriate term.
What are explanatory and response variables?: The difference between explanatory and response variables is simple:

An explanatory variable is the expected cause, and it explains the results.

A response variable is the expected effect, and it responds to other variables.
What are the requirements for a controlled experiment?: In a controlled experiment, all extraneous variables are held constant so that they can’t influence the results. Controlled experiments require:

A control group that receives a standard treatment, a fake treatment, or no treatment.

Random assignment of participants to ensure the groups are equivalent.

Depending on your study topic, there are various other methods of controlling variables.
How do I include an image in my paper in Chicago style?: In Chicago style, when you don’t just refer to an image but actually include it in your paper, the image should be formatted as a figure. Place the figure before or after the first paragraph where it is mentioned. Refer to figures by their numbers in the text (e.g. “see fig. 1”).

Below the figure, place a caption providing the figure number followed by a period (e.g. “Figure 1.”), a reference to the source (if you didn’t create the image yourself), and any relevant information to help the reader understand the image (if needed).

The caption is single-spaced and left-aligned, and followed by a blank line before the continuation of the main text.
What are the types of extraneous variables?: There are 4 main types of extraneous variables:

Demand characteristics: environmental cues that encourage participants to conform to researchers’ expectations.

Experimenter effects: unintentional actions by researchers that influence study outcomes.

Situational variables: environmental variables that alter participants’ behaviors.

Participant variables: any characteristic or aspect of a participant’s background that could affect study results.
What’s the difference between extraneous and confounding variables?: An extraneous variable is any variable that you’re not investigating that can potentially affect the dependent variable of your research study.

A confounding variable is a type of extraneous variable that not only affects the dependent variable, but is also related to the independent variable.
What statistical results do you need to report according to APA style?: According to the APA guidelines, you should report enough detail on inferential statistics so that your readers understand your analyses.

Report the following for each hypothesis test:

the test statistic value

the degrees of freedom

the exact p value (unless it is less than 0.001)

the magnitude and direction of the effect

You should also present confidence intervals and estimates of effect sizes where relevant.
How many decimal places do you use in APA style?: The number of decimal places to report depends on what you’re reporting. Generally, you should aim to round numbers while retaining precision. It’s best to present fewer decimal digits to aid easy understanding.

Use one decimal place for:

Means

Standard deviations

Descriptive statistics based on discrete data

Use two decimal places for:

Correlation coefficients

Proportions

Inferential test statistics such as t values, F values, and chi-squares.
Do I need a citation when I quote or paraphrase an interview?: For a published interview (whether in video, audio, or print form), you should always include a citation, just as you would for any other source.

For an interview you conducted yourself, formally or informally, you often don’t need a citation and can just refer to it in the text or in a footnote, since the reader won’t be able to look them up anyway. MLA, however, still recommends including citations for your own interviews.
What are the main elements of an interview citation?: The main elements included in a newspaper interview citation across APA, MLA, and Chicago style are the names of the interviewer and interviewee, the interview title, the publication date, the name of the newspaper, and a URL (for online sources).

The information is presented differently in different citation styles. One key difference is that APA advises listing the interviewer in the author position, while MLA and Chicago advise listing the interviewee first.
What is a factorial design?: In a factorial design, multiple independent variables are tested.

If you test two variables, each level of one independent variable is combined with each level of the other independent variable to create different conditions.
What are the pros and cons of a within-subjects design?: Within-subjects designs have many potential threats to internal validity, but they are also very statistically powerful.

Advantages:

Only requires small samples,

Statistically powerful,

Removes the effects of individual differences on the outcomes.

Disadvantages:

Internal validity threats reduce the likelihood of establishing a direct relationship between variables,

Time-related effects, such as growth, can influence the outcomes,

Carryover effects mean that the specific order of different treatments affect the outcomes.
Which types of graduate programs require interviews?: Most medical school programs interview candidates, as do many (though not all) leading law and business schools.

In research programs, it depends—PhDs in business usually do, while those in economics normally do not, for example.

Some schools interview everyone, while others only interview their top candidates. Look at the websites of the schools you’re applying to for more information on whether they conduct interviews.
How do I properly prepare for a graduate school interview?: In addition to thinking about your answers for the most commonly asked grad school interview questions, you should reach out to former and current students to ask their advice on preparing and what sort of questions will be asked.

Look back through your resume and come up with anecdotes that you could use for common questions, particularly those that ask about obstacles that you overcame. If you’re applying for a research program, ensure that you can talk about the previous research experience you’ve had.

You should also read as much research in your field as possible. Research the faculty at the schools you’re applying to and read some of their papers. Come up with a few questions that you could ask them.
What are the most common graduate school interview questions?: Graduate schools often ask questions about why you are interested in this particular program and what you will contribute.

Try to stay away from cliche answers like “this is a good program” or “I got good grades in undergrad” and focus instead on the unique strengths of the program or what you will bring to the table. Understand what the program is looking for and come up with anecdotes that demonstrate why you are a good fit for them.

Different types of programs may also focus on different questions:

Research programs will often ask what topics you’d like to research and who you would like to work with, as well as specific questions about your research background.

Medical schools are interested in your personal motivation, qualities such as integrity and empathy, and how you’d respond to common ethical dilemmas.

Business schools will focus on your past work experience and future career prospects, and may be particularly interested in any experience you have managing or working with others.
What are the main elements of a newspaper article citation?: The elements included in a newspaper article citation across APA, MLA, and Chicago style are the author name, the article title, the publication date, the newspaper name, and the URL if the article was accessed online.

In APA and MLA, the page numbers of the article appear in place of the URL if the article was accessed in print. No page numbers are used in Chicago newspaper citations.
How do I cite a source with no title?: Untitled sources (e.g. some images) are usually cited using a short descriptive text in place of the title. In APA Style, this description appears in brackets: [Chair of stained oak]. In MLA and Chicago styles, no brackets are used: Chair of stained oak.

For social media posts, which are usually untitled, quote the initial words of the post in place of the title: the first 160 characters in Chicago, or the first 20 words in APA. E.g. Biden, J. [@JoeBiden]. “The American Rescue Plan means a $7,000 check for a single mom of four. It means more support to safely.”

MLA recommends quoting the full post for something short like a tweet, and just describing the post if it’s longer.
What are the main elements of an image citation?: The main elements included in image citations across APA, MLA, and Chicago style are the name of the image’s creator, the image title, the year (or more precise date) of publication, and details of the container in which the image was found (e.g. a museum, book, website).

In APA and Chicago style, it’s standard to also include a description of the image’s format (e.g. “Photograph” or “Oil on canvas”). This sort of information may be included in MLA too, but is not mandatory.
What are the main elements of a lecture citation?: The main elements included in a lecture citation across APA, MLA, and Chicago style are the name of the speaker, the lecture title, the date it took place, the course or event it was part of, and the institution it took place at.

For transcripts or recordings of lectures/speeches, other details like the URL, the name of the book or website, and the length of the recording may be included instead of information about the event and institution.
What are the main elements of a YouTube citation?: The main elements included in a YouTube video citation across APA, MLA, and Chicago style are the name of the author/uploader, the title of the video, the publication date, and the URL.

The format in which this information appears is different for each style.

All styles also recommend using timestamps as a locator in the in-text citation or footnote.
What are the pros and cons of a between-subjects design?: While a between-subjects design has fewer threats to internal validity, it also requires more participants for high statistical power than a within-subjects design.

Advantages:

Prevents carryover effects of learning and fatigue.

Shorter study duration.

Disadvantages:

Needs larger samples for high power.

Uses more resources to recruit participants, administer sessions, cover costs, etc.

Individual differences may be an alternative explanation for results.
Can you use a between- and within-subjects design in the same study?: Yes. Between-subjects and within-subjects designs can be combined in a single study when you have two or more independent variables (a factorial design). In a mixed factorial design, one variable is altered between subjects and another is altered within subjects.
What’s the difference between within-subjects and between-subjects designs?: In a between-subjects design, every participant experiences only one condition, and researchers assess group differences between participants in various conditions.

In a within-subjects design, each participant experiences all conditions, and researchers test the same participants repeatedly for differences between conditions.

The word “between” means that you’re comparing different conditions between groups, while the word “within” means you’re comparing different conditions within the same group.
How can I make a suggestion for the Knowledge Base?: We’re always striving to improve the Knowledge Base. If you have an idea for a topic we should cover, or you notice a mistake in any of our articles, let us know by emailing shona@scribbr.com.
Can I use Scribbr content for educational purposes?: Yes! We’re happy for educators to use our content, and we’ve even adapted some of our articles into ready-made lecture slides.

You are free to display, distribute, and adapt Scribbr materials in your classes or upload them in private learning environments like Blackboard. This applies to articles, videos, images, and any other content published on the Knowledge Base. Video transcripts and subtitles can be accessed on YouTube. Please credit Scribbr for creating any materials you use in your teaching.

You may not republish, adapt, or translate our materials for public distribution without permission. If you have ideas for adapting Scribbr content, email shona@scribbr.com.
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Create your citations and manage your reference list with our free Citation Generators in APA and MLA style.

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Who is the Knowledge Base for?: The Knowledge Base is for students at all levels. Whether you’re writing your first essay, working on your bachelor’s or master’s thesis, or getting to grips with your PhD research, we’ve got you covered.
What is the Scribbr Knowledge Base?: The Scribbr Knowledge Base is a collection of free resources to help you succeed in academic research, writing, and citation. Every week, we publish helpful step-by-step guides, clear examples, simple templates, engaging videos, and more.
How do I write an annotation for a source?: Each annotation in an annotated bibliography is usually between 50 and 200 words long. Longer annotations may be divided into paragraphs.

The content of the annotation varies according to your assignment. An annotation can be descriptive, meaning it just describes the source objectively; evaluative, meaning it assesses its usefulness; or reflective, meaning it explains how the source will be used in your own research.
What types of sources should I use in an annotated bibliography?: Any credible sources on your topic can be included in an annotated bibliography, but you should usually focus on collecting journal articles and scholarly books.
What is an annotated bibliography?: An annotated bibliography is an assignment where you collect sources on a specific topic and write an annotation for each source. An annotation is a short text that describes and sometimes evaluates the source.
What are the main elements of a journal article citation?: The elements included in journal article citations across APA, MLA, and Chicago style are the name(s) of the author(s), the title of the article, the year of publication, the name of the journal, the volume and issue numbers, the page range of the article, and, when accessed online, the DOI or URL.

In MLA and Chicago style, you also include the specific month or season of publication alongside the year, when this information is available.
When do you use random assignment?: Random assignment is used in experiments with a between-groups or independent measures design. In this research design, there’s usually a control group and one or more experimental groups. Random assignment helps ensure that the groups are comparable.

In general, you should always use random assignment in this type of experimental design when it is ethically possible and makes sense for your study topic.
How do you randomly assign participants to groups?: To implement random assignment, assign a unique number to every member of your study’s sample.

Then, you can use a random number generator or a lottery method to randomly assign each number to a control or experimental group. You can also do so manually, by flipping a coin or rolling a dice to randomly assign participants to groups.
What’s the difference between random assignment and random selection?: Random selection, or random sampling, is a way of selecting members of a population for your study’s sample.

In contrast, random assignment is a way of sorting the sample into control and experimental groups.

Random sampling enhances the external validity or generalizability of your results, while random assignment improves the internal validity of your study.
What is random assignment?: In experimental research, random assignment is a way of placing participants from your sample into different groups using randomization. With this method, every member of the sample has a known or equal chance of being placed in a control group or an experimental group.
How do I cite a source with no author?: In APA, MLA, and Chicago style citations for sources that don’t list a specific author (e.g. many websites), you can usually list the organization responsible for the source as the author.

If the organization is the same as the website or publisher, you shouldn’t repeat it twice in your reference:

In APA and Chicago, omit the website or publisher name later in the reference.

In MLA, omit the author element at the start of the reference, and cite the source title instead.

If there’s no appropriate organization to list as author, you will usually have to begin the citation and reference entry with the title of the source instead.
What are the main elements of a website citation?: The main elements included in website citations across APA, MLA, and Chicago style are the author, the date of publication, the page title, the website name, and the URL. The information is presented differently in each style.
What does “controlling for a variable” mean?: “Controlling for a variable” means measuring extraneous variables and accounting for them statistically to remove their effects on other variables.

Researchers often model control variable data along with independent and dependent variable data in regression analyses and ANCOVAs. That way, you can isolate the control variable’s effects from the relationship between the variables of interest.
Why are control variables important?: Control variables help you establish a correlational or causal relationship between variables by enhancing internal validity.

If you don’t control relevant extraneous variables, they may influence the outcomes of your study, and you may not be able to demonstrate that your results are really an effect of your independent variable.
What is a control variable?: A control variable is any variable that’s held constant in a research study. It’s not a variable of interest in the study, but it’s controlled because it could influence the outcomes.
Why should you include mediators and moderators in a study?: Including mediators and moderators in your research helps you go beyond studying a simple relationship between two variables for a fuller picture of the real world. They are important to consider when studying complex correlational or causal relationships.

Mediators are part of the causal pathway of an effect, and they tell you how or why an effect takes place. Moderators usually help you judge the external validity of your study by identifying the limitations of when the relationship between variables holds.
How can you tell if something is a mediator?: If something is a mediating variable:

It’s caused by the independent variable.

It influences the dependent variable

When it’s taken into account, the statistical correlation between the independent and dependent variables is higher than when it isn’t considered.
What’s the difference between a confounder and a mediator?: A confounder is a third variable that affects variables of interest and makes them seem related when they are not. In contrast, a mediator is the mechanism of a relationship between two variables: it explains the process by which they are related.
What’s the difference between a mediator and a moderator?: A mediator variable explains the process through which two variables are related, while a moderator variable affects the strength and direction of that relationship.
How do I cite a source with no page numbers?: When you want to cite a specific passage in a source without page numbers (e.g. an e-book or website), all the main citation styles recommend using an alternate locator in your in-text citation. You might use a heading or chapter number, e.g. (Smith, 2016, ch. 1)

In APA Style, you can count the paragraph numbers in a text to identify a location by paragraph number. MLA and Chicago recommend that you only use paragraph numbers if they’re explicitly marked in the text.

For audiovisual sources (e.g. videos), all styles recommend using a timestamp to show a specific point in the video when relevant.
When should I use “et al.” in citations?: The abbreviation “et al.” (Latin for “and others”) is used to shorten citations of sources with multiple authors.

In APA Style, “et al.” is used in in-text citations of sources with 3+ authors, e.g. (Smith et al., 2019). It is not used in reference entries.

In MLA style, use “et al.” for 3+ authors in in-text citations and Works Cited entries.

In Chicago style, use “et al.” for 4+ authors in an in-text citation, and for 10+ authors in a bibliography entry.
Which citation style should I use?: Check if your university or course guidelines specify which citation style to use. If the choice is left up to you, consider which style is most commonly used in your field.

APA Style is the most popular citation style, widely used in the social and behavioral sciences.

MLA style is the second most popular, used mainly in the humanities.

Chicago notes and bibliography style is also popular in the humanities, especially history.

Chicago author-date style tends to be used in the sciences.

Other more specialized styles exist for certain fields, such as Bluebook and OSCOLA for law.

The most important thing is to choose one style and use it consistently throughout your text.
What are the main elements of a book citation?: The main elements included in all book citations across APA, MLA, and Chicago style are the author, the title, the year of publication, and the name of the publisher. A page number is also included in in-text citations to highlight the specific passage cited.

In Chicago style and in the 6th edition of APA Style, the location of the publisher is also included, e.g. London: Penguin.
How do you increase statistical power?: There are various ways to improve power:

Increase the potential effect size by manipulating your independent variable more strongly,

Increase sample size,

Increase the significance level (alpha),

Reduce measurement error by increasing the precision and accuracy of your measurement devices and procedures,

Use a one-tailed test instead of a two-tailed test for t tests and z tests.
What is a power analysis?: A power analysis is a calculation that helps you determine a minimum sample size for your study. It’s made up of four main components. If you know or have estimates for any three of these, you can calculate the fourth component.

Statistical power: the likelihood that a test will detect an effect of a certain size if there is one, usually set at 80% or higher.

Sample size: the minimum number of observations needed to observe an effect of a certain size with a given power level.

Significance level (alpha): the maximum risk of rejecting a true null hypothesis that you are willing to take, usually set at 5%.

Expected effect size: a standardized way of expressing the magnitude of the expected result of your study, usually based on similar studies or a pilot study.
At what point in life should I apply for graduate school?: Some students apply to graduate school straight from undergrad, but it’s also common to go back to school later in life. The ideal time to do so depends on various financial, personal, and career considerations. Graduate school is a big commitment, so you should apply at a time when you can devote your full attention to it.

Your career path may also determine when you should apply. In some career fields, you can easily progress without a graduate degree, while in others—such as medicine, business, and law—it’s virtually impossible to move up the career ladder without a specific graduate degree.
When are graduate school application deadlines?: Most graduate school applications for American graduate programs are due in December or January for a September start.

Some types of programs, especially law school, are rolling applications, meaning that the earlier you apply, the earlier you’ll hear back. In this case, you should aim to apply as early as possible to maximize your chances.

Medical school follows a completely separate timeline with much earlier deadlines. If you’re applying for medical school, you should speak to advisors at your university for more information.
When should I begin my applications for graduate school?: A good starting point to aim for is about 18 months before you would start the program, or 6–9 months before the applications are due.

In the first few months of the process, research programs and study for any standardized exams you might need.

You can then begin writing your personal statements and statements of purpose, as well as contacting people to write your letters of recommendation. Ensure that you give recommenders plenty of time to complete their letters (ideally around 2–4 months).
What are null and alternative hypotheses?: In statistical hypothesis testing, the null hypothesis of a test always predicts no effect or no relationship between variables, while the alternative hypothesis states your research prediction of an effect or relationship.
What is statistical analysis?: Statistical analysis is the main method for analyzing quantitative research data. It uses probabilities and models to test predictions about a population from sample data.
Do I need to include a URL in an APA legal reference?: No, including a URL is optional in APA Style reference entries for legal sources (e.g. court cases, laws). It can be useful to do so to aid the reader in retrieving the source, but it’s not required, since the other information included should be enough to locate it.
Should I cite laws using public law numbers in APA Style?: Generally, you should identify a law in an APA reference entry by its location in the United States Code (U.S.C.).

But if the law is either spread across various sections of the code or not featured in the code at all, include the public law number in addition to information on the source you accessed the law in, e.g.:

Lilly Ledbetter Fair Pay Act of 2009, Pub. L. No. 111-2, 123 Stat. 5 (2009).
What tense should I write the methods section in?: You should report methods using the past tense, even if you haven’t completed your study at the time of writing. That’s because the methods section is intended to describe completed actions or research.
What should I include in an APA methods section?: In your APA methods section, you should report detailed information on the participants, materials, and procedures used.

Describe all relevant participant or subject characteristics, the sampling procedures used and the sample size and power.

Define all primary and secondary measures and discuss the quality of measurements.

Specify the data collection methods, the research design and data analysis strategy, including any steps taken to transform the data and statistical analyses.
What doesn’t go in an essay conclusion?: For a stronger conclusion paragraph, avoid including:

Important evidence or analysis that wasn’t mentioned in the main body

Generic concluding phrases (e.g. “In conclusion…”)

Weak statements that undermine your argument (e.g. “There are good points on both sides of this issue.”)

Your conclusion should leave the reader with a strong, decisive impression of your work.
What goes in an essay conclusion?: Your essay’s conclusion should contain:

A rephrased version of your overall thesis

A brief review of the key points you made in the main body

An indication of why your argument matters

The conclusion may also reflect on the broader implications of your argument, showing how your ideas could applied to other contexts or debates.
How long is an essay conclusion?: The conclusion paragraph of an essay is usually shorter than the introduction. As a rule, it shouldn’t take up more than 10–15% of the text.
How do I cite a court case reported in multiple publications in APA Style?: With APA legal citations, it’s recommended to cite all the reporters (publications reporting cases) in which a court case appears. To cite multiple reporters, just separate them with commas in your reference entry. This is called parallel citation.

Don’t repeat the name of the case, court, or year; just list the volume, reporter, and page number for each citation. For example:

Brown v. Collins, 541 U.S. 948, 2004 U.S. LEXIS 2215, 124 S. Ct. 1684, 158 L. Ed. 2d 377, 72 U.S.L.W. 3598 (U.S. 2004).
How do I cite a court case with no page number in APA Style?: In APA Style, when you’re citing a recent court case that has not yet been reported in print and thus doesn’t have a specific page number, include a series of three underscores (___) where the page number would usually appear:

Chicago v. Fulton, 592 U.S. ___ (2021). https://www.supremecourt.gov/opinions/20pdf/19-357_6k47.pdf
How do I cite multiple Shakespeare plays in an MLA paper?: If you cite multiple Shakespeare plays throughout your MLA paper, the in-text citation begins with an abbreviated version of the title (as shown here), e.g. (Oth. 1.2.4). Each play should have its own Works Cited entry (even if they all come from the same collection).

If you cite only one Shakespeare play in your paper, you should include a Works Cited entry for that play, and your in-text citations should start with the author’s name, e.g. (Shakespeare 1.1.4).
Should I use page numbers in a Shakespeare citation in MLA?: No, do not use page numbers in your MLA in-text citations of Shakespeare plays. Instead, specify the act, scene, and line numbers of the quoted material, separated by periods, e.g. (Shakespeare 3.2.20–25).

This makes it easier for the reader to find the relevant passage in any edition of the text.
How do you reduce the risk of making a Type II error?: The risk of making a Type II error is inversely related to the statistical power of a test. Power is the extent to which a test can correctly detect a real effect when there is one.

To (indirectly) reduce the risk of a Type II error, you can increase the sample size or the significance level to increase statistical power.
How do you reduce the risk of making a Type I error?: The risk of making a Type I error is the significance level (or alpha) that you choose. That’s a value that you set at the beginning of your study to assess the statistical probability of obtaining your results (p value).

The significance level is usually set at 0.05 or 5%. This means that your results only have a 5% chance of occurring, or less, if the null hypothesis is actually true.

To reduce the Type I error probability, you can set a lower significance level.
What are Type I and Type II errors?: In statistics, a Type I error means rejecting the null hypothesis when it’s actually true, while a Type II error means failing to reject the null hypothesis when it’s actually false.
How do I cite an article spread across non-consecutive pages in MLA?: When an article (e.g. in a newspaper) appears on non-consecutive pages (e.g. starting on page 1 and continuing on page 6), you should use “pp.” in your Works Cited entry, since it’s on multiple pages, but MLA recommends just listing the first page followed by a plus sign, e.g. pp. 1+.
How do I cite a local newspaper in MLA?: In an MLA style Works Cited entry for a newspaper, you can cite a local newspaper in the same way as you would a national one, except that you may have to add the name of the city in square brackets to clarify what newspaper you mean, e.g. The Gazette [Montreal].

Do not add the city name in brackets if it’s already part of the newspaper’s name, e.g. Dallas Observer.
Who is listed as the author of a TV show in MLA?: MLA doesn’t require you to list an author for a TV show. If your citation doesn’t focus on a particular contributor, just start your Works Cited entry with the title of the episode or series, and use this (shortened if necessary) in your in-text citation.

If you focus on a particular contributor (e.g. the writer or director, a particular actor), you can list them in the author position, along with a label identifying their role.
Who is listed as the author of a podcast in MLA?: It’s standard to list the podcast’s host in the author position, accompanied by the label “host,” in an MLA Works Cited entry. It’s sometimes more appropriate to use the label “narrator,” when the podcast just tells a story without any guests.

If your citation of the podcast focuses more on the contribution of someone else (e.g. a guest, the producer), they can be listed in the author position instead, with an appropriate label.
What is statistical power?: In statistics, power refers to the likelihood of a hypothesis test detecting a true effect if there is one. A statistically powerful test is more likely to reject a false negative (a Type II error).

If you don’t ensure enough power in your study, you may not be able to detect a statistically significant result even when it has practical significance. Your study might not have the ability to answer your research question.
What’s the difference between statistical and practical significance?: While statistical significance shows that an effect exists in a study, practical significance shows that the effect is large enough to be meaningful in the real world.

Statistical significance is denoted by p-values whereas practical significance is represented by effect sizes.
How do I calculate effect size?: There are dozens of measures of effect sizes. The most common effect sizes are Cohen’s d and Pearson’s r. Cohen’s d measures the size of the difference between two groups while Pearson’s r measures the strength of the relationship between two variables.
What is effect size?: Effect size tells you how meaningful the relationship between variables or the difference between groups is.

A large effect size means that a research finding has practical significance, while a small effect size indicates limited practical applications.
When should I use tables or figures to present numbers?: In APA style, statistics can be presented in the main text or as tables or figures. To decide how to present numbers, you can follow APA guidelines:

To present three or fewer numbers, try a sentence,

To present between 4 and 20 numbers, try a table,

To present more than 20 numbers, try a figure.

Since these are general guidelines, use your own judgment and feedback from others for effective presentation of numbers.
What should I include in an APA results section?: In an APA results section, you should generally report the following:

Participant flow and recruitment period.

Missing data and any adverse events.

Descriptive statistics about your samples.

Inferential statistics, including confidence intervals and effect sizes.

Results of any subgroup or exploratory analyses, if applicable.
What’s the difference between a point estimate and an interval estimate?: Using descriptive and inferential statistics, you can make two types of estimates about the population: point estimates and interval estimates.

A point estimate is a single value estimate of a parameter. For instance, a sample mean is a point estimate of a population mean.

An interval estimate gives you a range of values where the parameter is expected to lie. A confidence interval is the most common type of interval estimate.

Both types of estimates are important for gathering a clear idea of where a parameter is likely to lie.
What’s the difference between standard error and standard deviation?: Standard error and standard deviation are both measures of variability. The standard deviation reflects variability within a sample, while the standard error estimates the variability across samples of a population.
What is standard error?: The standard error of the mean, or simply standard error, indicates how different the population mean is likely to be from a sample mean. It tells you how much the sample mean would vary if you were to repeat a study using new samples from within a single population.
Who is listed as the author of a podcast in APA Style?: When citing a podcast episode in APA Style, the podcast’s host is listed as author, accompanied by a label identifying their role, e.g. Glass, I. (Host).

When citing a whole podcast series, if different episodes have different hosts, list the executive producer(s) instead. Again, include a label identifying their role, e.g. Lechtenberg, S. (Producer).
How do I cite a specific passage from the Bible in APA Style?: Like most style guides, APA recommends listing the book of the Bible you’re citing in your in-text citation, in combination with chapter and verse numbers. For example:

(English Standard Version Bible, 2001, 1 Cor. 14:1)

Books of the Bible may be abbreviated to save space; a list of standard abbreviations can be found here. Page numbers are not used in Bible citations.
Do I need to include the Bible in my reference list in APA Style?: Yes, in the 7th edition of APA Style, versions of the Bible are treated much like other books; you should include the edition you used in your reference list.

Previously, in the 6th edition of the APA manual, it was recommended to just use in-text citations to refer to the Bible, and omit it from the reference list.
Can I cite a source quoted in another source in MLA?: MLA recommends citing the original source wherever possible, rather than the source in which it is quoted or reproduced.

If this isn’t possible, cite the secondary source and use “qtd. in” (quoted in) in your in-text citation. For example: (qtd. in Smith 233)

If a source is reproduced in full within another source (e.g. an image within a PowerPoint or a poem in an article), give details of the original source first, then include details of the secondary source as a container. For example:

Picasso, Pablo. Guernica. 1937. Introduction to Art History, taught by James Wilson, 24 Sep. 2019, Duke University, Durham. Slide 7.
How do I cite lecture materials I viewed in person in MLA?: When you want to cite a PowerPoint or lecture notes from a lecture you viewed in person in MLA, check whether they can also be accessed online; if so, this is the best version to cite, as it allows the reader to access the source.

If the material is not available online, use the details of where and when the presentation took place.
Whom should I list as the author of a YouTube video in APA Style?: To make it easy for the reader to find the YouTube video, in APA Style you list the person or organization who uploaded the video as the author in your reference entry and in-text citation.

If this isn’t the same person responsible for the content of the video, you might want to make this clear in the text. For example:

Nisha Anand (TED, 2020) states that …
How do I cite a quote from a video or audio source in APA Style?: When you need to highlight a specific moment in a video or audio source, APA Style recommends using a timestamp in your in-text citation. Just include the timestamp from the start of the part you’re citing. For example:

(TED, 2020, 1:59).
Do I need to give details about the album in an MLA song citation?: In an MLA song citation, you need to give some sort of container to indicate how you accessed the song. If this is a physical or downloaded album, the Works Cited entry should list the album name, distributor, year, and format.

However, if you listened to the song on a streaming service, you can just list the site as a container, including a URL. In this case, including the album details is optional; you may add this information if it is relevant to your discussion or if it will help the reader access the song.
Whom do I cite as the author of a song in MLA Style?: When citing a song in MLA style, the author is usually the main artist or group that released the song.

However, if your discussion focuses on the contributions of a specific performer, e.g. a guitarist or singer, you may list them as author, even if they are not the main artist. If you’re discussing the lyrics or composition, you may cite the songwriter or composer rather than a performer.
How do you know whether a number is a parameter or a statistic?: To figure out whether a given number is a parameter or a statistic, ask yourself the following:

Does the number describe a whole, complete population where every member can be reached for data collection?

Is it possible to collect data for this number from every member of the population in a reasonable time frame?

If the answer is yes to both questions, the number is likely to be a parameter. For small populations, data can be collected from the whole population and summarized in parameters.

If the answer is no to either of the questions, then the number is more likely to be a statistic.
How do I apply for a master’s or a PhD?: In the US, the graduate school application process is similar whether you’re applying for a master’s or a PhD. Both require letters of recommendation, a statement of purpose or personal statement, a resume or CV, and transcripts. Programs in the US and Canada usually also require a certain type of standardized test—often the GRE.

Outside the US, PhD programs usually also require applicants to write a research proposal, because students are expected to begin dissertation research in the first year of their PhD.
Is it more expensive to get a master’s or a PhD?: A master’s degree usually has a higher upfront cost, but it also allows you to start earning a higher salary more quickly. The exact cost depends on the country and the school: private universities usually cost more than public ones, and European degrees usually cost less than North American ones. There are limited possibilities for financial aid.

PhDs often waive tuition fees and offer a living stipend in exchange for a teaching or research assistantship. However, they take many years to complete, during which time you earn very little.
Do I need a master’s degree to apply for a PhD?: This depends on the country. In the United States, you can generally go directly to a PhD with only a bachelor’s degree, as a master’s program is included as part of the doctoral program.

Elsewhere, you generally need to graduate from a research-intensive master’s degree before continuing to the PhD.
How long does it take to get a PhD?: This varies by country. In the United States, PhDs usually take between 5–7 years: 2 years of coursework followed by 3–5 years of independent research work to produce a dissertation.

In the rest of the world, students normally have a master’s degree before beginning the PhD, so they proceed directly to the research stage and complete a PhD in 3–5 years.
What is a PhD?: A PhD, which is short for philosophiae doctor (doctor of philosophy in Latin), is the highest university degree that can be obtained. In a PhD, students spend 3–5 years writing a dissertation, which aims to make a significant, original contribution to current knowledge.

A PhD is intended to prepare students for a career as a researcher, whether that be in academia, the public sector, or the private sector.
What is a master’s?: A master’s is a 1- or 2-year graduate degree that can prepare you for a variety of careers.

All master’s involve graduate-level coursework. Some are research-intensive and intend to prepare students for further study in a PhD; these usually require their students to write a master’s thesis. Others focus on professional training for a specific career.
How can I summarize a source without plagiarizing?: To avoid plagiarism when summarizing an article or other source, follow these two rules:

Write the summary entirely in your own words by paraphrasing the author’s ideas.

Cite the source with an in-text citation and a full reference so your reader can easily find the original text.
How long is a summary?: A summary is always much shorter than the original text. The length of a summary can range from just a few sentences to several paragraphs; it depends on the length of the article you’re summarizing, and on the purpose of the summary.
What is a summary?: A summary is a short overview of the main points of an article or other source, written entirely in your own words.
How do I cite a source with no title in MLA style?: When a source has no title, this part of your MLA reference is replaced with a description of the source, in plain text (no italics or quotation marks, sentence-case capitalization).

Mackintosh, Charles Rennie. Chair of stained oak. 1897–1900, Victoria and Albert Museum, London.
When do I need to include an image citation in MLA style?: Whenever you refer to an image created by someone else in your text, you should include a citation leading the reader to the image you’re discussing.

If you include the image directly in your text as a figure, the details of the source appear in the figure’s caption. If you don’t, just include an in-text citation wherever you mention the image, and an entry in the Works Cited list giving full details.
How do I format a paper in Chicago style?: The main guidelines for formatting a paper in Chicago style are to:

Use a standard font like 12 pt Times New Roman

Use 1 inch margins or larger

Apply double line spacing

Indent every new paragraph ½ inch

Include a title page

Place page numbers in the top right or bottom center

Cite your sources with author-date citations or footnotes

Include a bibliography or reference list
How do I format a paper in MLA style?: The main guidelines for formatting a paper in MLA style are as follows:

Use an easily readable font like 12 pt Times New Roman

Set 1 inch page margins

Apply double line spacing

Include a four-line MLA heading on the first page

Center the paper’s title

Indent every new paragraph ½ inch

Use title case capitalization for headings

Cite your sources with MLA in-text citations

List all sources cited on a Works Cited page at the end
How do I format a paper in APA Style?: To format a paper in APA Style, follow these guidelines:

Use a standard font like 12 pt Times New Roman or 11 pt Arial

Set 1 inch page margins

Apply double line spacing

Include a title page

If submitting for publication, insert a running head on every page

Indent every new paragraph ½ inch

Apply APA heading styles

Cite your sources with APA in-text citations

List all sources cited on a reference page at the end
How do I quote in APA format?: To include a direct quote in APA, follow these rules:

Quotes under 40 words are placed in double quotation marks.

Quotes of 40 words or more are formatted as block quote.

The author, year, and page number are included in an in-text citation.
What is a block quote?: A block quote is a long quote formatted as a separate “block” of text. Instead of using quotation marks, you place the quote on a new line, and indent the entire quote to mark it apart from your own words.

The rules for when to apply block quote formatting depend on the citation style:

APA block quotes are 40 words or longer.

MLA block quotes are more than 4 lines of prose or 3 lines of poetry.

Chicago block quotes are longer than 100 words.
When should I use quotes?: In academic writing, there are three main situations where quoting is the best choice:

To analyze the author’s language (e.g. in a literary analysis essay).

To give evidence from primary sources.

To accurately present a precise definition or argument.

Don’t overuse quotes; your own voice should be dominant. If you just want to provide information from a source, it’s usually better to paraphrase or summarize.
How do I cite a quote in academic writing?: Every time you quote a source, you must include a correctly formatted in-text citation. This looks slightly different depending on the citation style.

For example, a direct quote in APA is cited like this: “This is a quote” (Streefkerk, 2020, p. 5).

Every in-text citation should also correspond to a full reference at the end of your paper.
What is a quote?: A quote is an exact copy of someone else’s words, usually enclosed in quotation marks and credited to the original author or speaker.
Should I include lists of my tables and figures in an APA paper?: APA doesn’t require you to include a list of tables or a list of figures. However, it is advisable to do so if your text is long enough to feature a table of contents and it includes a lot of tables and/or figures.

A list of tables and list of figures appear (in that order) after your table of contents, and are presented in a similar way.
How can I find copyright information on tables and figures from other sources?: Copyright information can usually be found wherever the table or figure was published. For example, for a diagram in a journal article, look on the journal’s website or the database where you found the article. Images found on sites like Flickr are listed with clear copyright information.

If you find that permission is required to reproduce the material, be sure to contact the author or publisher and ask for it.
Should I include tables and figures in my APA reference list?: If you adapt or reproduce a table or figure from another source, you should include that source in your APA reference list. You should also include copyright information in the note for the table or figure, and include an in-text citation when you refer to it.

Tables and figures you created yourself, based on your own data, are not included in the reference list.
Should I place the in-text citation before or after the period?: An APA in-text citation is placed before the final punctuation mark in a sentence.

The company invested over 40,000 hours in optimizing its algorithm (Davis, 2011).

A recent poll suggests that EU membership “would be backed by 55 percent of Danish voters” in a referendum (Levring, 2018).
How do I cite an indirect source in APA Style? (“as cited in”): In an APA in-text citation, you use the phrase “as cited in” if you want to cite a source indirectly (i.e., if you cannot find the original source).

Parenthetical citation: (Brown, 1829, as cited in Mahone, 2018)
Narrative citation: Brown (1829, as cited in Mahone, 2018) states that…

On the reference page, you only include the secondary source (Mahone, 2018).
Is there a tool that can order my references automatically?: Popular word processors like Microsoft Word and Google Docs can order lists in alphabetical order, but they don’t follow the APA Style alphabetization guidelines.

If you use Scribbr’s APA Citation Generator to create citations, references are ordered automatically based on the APA guidelines, taking into account all the exceptions.
How do I order works whose title starts with a numeral?: Order numerals as though they were spelled out:

“20 tips to relax” is ordered on the “T” of “Twenty”.

“100 cities you should visit” is ordered on the “O” of “One hundred”.

Read more about alphabetizing the APA reference page.
How do I order works that have no author?: If the author of a work is unknown, order the reference by its title. Disregard the words “A”, “An”, and “The” at the beginning of the title.

The privacy concerns around social media

Teens, social media, and privacy

Read more about alphabetizing the APA reference page.
What do I say when asking for a letter of recommendation?: It’s best to ask in person if possible, so first reach out and request a meeting to discuss your graduate school plans.

Let the potential recommender know which programs you’re applying to, and ask if they feel they can provide a strong letter of recommendation. A lukewarm recommendation can be the kiss of death for an application, so make sure your letter writers are enthusiastic about recommending you and your work!

Always remember to remain polite. Your recommenders are doing you a favor by taking the time to write a letter in support of your graduate school goals.
Can I ask non-professors for a letter of recommendation?: This depends on the program that you are applying for. Generally, for professional programs like business and policy school, you should ask managers who can speak to your future leadership potential and ability to succeed in your chosen career path.

However, in other graduate programs, you should mostly ask your former professors or research supervisors to write your recommendation letters, unless you have worked in a job that corresponds closely with your chosen field (e.g., as a full-time research assistant).
Who should I ask for a letter of recommendation?: Choose people who know your work well and can speak to your ability to succeed in the program that you are applying to.

Remember, it is far more important to choose someone who knows you well than someone well-known. You may have taken classes with more prominent professors, but if they haven’t worked closely with you, they probably can’t write you a strong letter.
Can I present new arguments in the conclusion of my research paper?: No, it’s not appropriate to present new arguments or evidence in the conclusion. While you might be tempted to save a striking argument for last, research papers follow a more formal structure than this.

All your findings and arguments should be presented in the body of the text (more specifically in the results and discussion sections if you are following a scientific structure). The conclusion is meant to summarize and reflect on the evidence and arguments you have already presented, not introduce new ones.
What should I include in a research paper conclusion?: The conclusion of a research paper has several key elements you should make sure to include:

A restatement of the research problem

A summary of your key arguments and/or findings

A short discussion of the implications of your research
When should I cite a book chapter in MLA?: In MLA Style, you should cite a specific chapter or work within a book in two situations:

When each of the book’s chapters is written by a different author.

When the book is a collection of self-contained works (such as poems, plays, or short stories), even if they are all written by the same author.

If you cite multiple chapters or works from the same book, include a separate Works Cited entry for each chapter.
Can I cite sources in an appendix?: Yes, if relevant you can and should include APA citations in your appendices. Use author-date citations as you do in the main text.

Any sources cited in your appendices should appear in your reference list. Do not create a separate reference list for your appendices.
Do I need to number my appendices in APA Style?: When you include more than one appendix in an APA Style paper, they should be labeled “Appendix A,” “Appendix B,” and so on.

When you only include a single appendix, it is simply called “Appendix” and referred to as such in the main text.

Referring to a single appendix
(see Appendix)
Where do appendices go in an APA Style paper?: Appendices in an APA Style paper appear right at the end, after the reference list and after your tables and figures if you’ve also included these at the end.
What is an appendix?: An appendix contains information that supplements the reader’s understanding of your research but is not essential to it. For example:

Interview transcripts

Questionnaires

Raw data

Detailed descriptions of equipment

Something is only worth including as an appendix if you refer to information from it at some point in the text (e.g. quoting from an interview transcript). If you don’t, it should probably be removed.
What are the different types of means?: The arithmetic mean is the most commonly used mean. It’s often simply called the mean or the average. But there are some other types of means you can calculate depending on your research purposes:

Weighted mean: some values contribute more to the mean than others.

Geometric mean: values are multiplied rather than summed up.

Harmonic mean: reciprocals of values are used instead of the values themselves.
How do I find the mean?: You can find the mean, or average, of a data set in two simple steps:

Find the sum of the values by adding them all up.

Divide the sum by the number of values in the data set.

This method is the same whether you are dealing with sample or population data or positive or negative numbers.
What is an essay?: An essay is a focused piece of writing that explains, argues, describes, or narrates.

In high school, you may have to write many different types of essays to develop your writing skills.

Academic essays at college level are usually argumentative: you develop a clear thesis about your topic and make a case for your position using evidence, analysis and interpretation.
What is a hook?: The “hook” is the first sentence of your essay introduction. It should lead the reader into your essay, giving a sense of why it’s interesting.

To write a good hook, avoid overly broad statements or long, dense sentences. Try to start with something clear, concise and catchy that will spark your reader’s curiosity.
What goes in an essay introduction?: Your essay introduction should include three main things, in this order:

An opening hook to catch the reader’s attention.

Relevant background information that the reader needs to know.

A thesis statement that presents your main point or argument.

The length of each part depends on the length and complexity of your essay.
When should I use the median?: The median is the most informative measure of central tendency for skewed distributions or distributions with outliers. For example, the median is often used as a measure of central tendency for income distributions, which are generally highly skewed.

Because the median only uses one or two values, it’s unaffected by extreme outliers or non-symmetric distributions of scores. In contrast, the mean and mode can vary in skewed distributions.
How do I find the median?: To find the median, first order your data. Then calculate the middle position based on n, the number of values in your data set.

If n is an odd number, the median lies at the position (n + 1) / 2.

If n is an even number, the median is the mean of the values at positions n / 2 and (n / 2) + 1.
Can there be more than one mode?: A data set can often have no mode, one mode or more than one mode – it all depends on how many different values repeat most frequently.

Your data can be:

without any mode

unimodal, with one mode,

bimodal, with two modes,

trimodal, with three modes, or

multimodal, with four or more modes.
How do I find the mode?: To find the mode:

If your data is numerical or quantitative, order the values from low to high.

If it is categorical, sort the values by group, in any order.

Then you simply need to identify the most frequently occurring value.
How do I perform systematic sampling?: There are three key steps in systematic sampling:

Define and list your population, ensuring that it is not ordered in a cyclical or periodic order.

Decide on your sample size and calculate your interval, k, by dividing your population by your target sample size.

Choose every kth member of the population as your sample.
What is systematic sampling?: Systematic sampling is a probability sampling method where researchers select members of the population at a regular interval – for example, by selecting every 15th person on a list of the population. If the population is in a random order, this can imitate the benefits of simple random sampling.
What are some examples of topic sentences?: Let’s say you’re writing a five-paragraph essay about the environmental impacts of dietary choices. Here are three examples of topic sentences you could use for each of the three body paragraphs:

Research has shown that the meat industry has severe environmental impacts.

However, many plant-based foods are also produced in environmentally damaging ways.

It’s important to consider not only what type of diet we eat, but where our food comes from and how it is produced.

Each of these sentences expresses one main idea – by listing them in order, we can see the overall structure of the essay at a glance. Each paragraph will expand on the topic sentence with relevant detail, evidence, and arguments.
Where does the topic sentence go in a paragraph?: The topic sentence usually comes at the very start of the paragraph.

However, sometimes you might start with a transition sentence to summarize what was discussed in previous paragraphs, followed by the topic sentence that expresses the focus of the current paragraph.
Why are topic sentences important?: Topic sentences help keep your writing focused and guide the reader through your argument.

In an essay or paper, each paragraph should focus on a single idea. By stating the main idea in the topic sentence, you clarify what the paragraph is about for both yourself and your reader.
What is a topic sentence?: A topic sentence is a sentence that expresses the main point of a paragraph. Everything else in the paragraph should relate to the topic sentence.
When should I use the interquartile range?: The interquartile range is the best measure of variability for skewed distributions or data sets with outliers. Because it’s based on values that come from the middle half of the distribution, it’s unlikely to be influenced by outliers.
What are the two main methods for calculating interquartile range?: The two most common methods for calculating interquartile range are the exclusive and inclusive methods.

The exclusive method excludes the median when identifying Q1 and Q3, while the inclusive method includes the median as a value in the data set in identifying the quartiles.

For each of these methods, you’ll need different procedures for finding the median, Q1 and Q3 depending on whether your sample size is even- or odd-numbered. The exclusive method works best for even-numbered sample sizes, while the inclusive method is often used with odd-numbered sample sizes.
What’s the difference between the range and interquartile range?: While the range gives you the spread of the whole data set, the interquartile range gives you the spread of the middle half of a data set.
When should I write my research paper introduction?: Don’t feel that you have to write the introduction first. The introduction is often one of the last parts of the research paper you’ll write, along with the conclusion.

This is because it can be easier to introduce your paper once you’ve already written the body; you may not have the clearest idea of your arguments until you’ve written them, and things can change during the writing process.
Should I use a research question, hypothesis, or thesis statement?: The way you present your research problem in your introduction varies depending on the nature of your research paper. A research paper that presents a sustained argument will usually encapsulate this argument in a thesis statement.

A research paper designed to present the results of empirical research tends to present a research question that it seeks to answer. It may also include a hypothesis—a prediction that will be confirmed or disproved by your research.
What should I include in a research paper introduction?: The introduction of a research paper includes several key elements:

A hook to catch the reader’s interest

Relevant background on the topic

Details of your research problem

A thesis statement or research question

Sometimes an overview of the paper
What is homoscedasticity?: Homoscedasticity, or homogeneity of variances, is an assumption of equal or similar variances in different groups being compared.

This is an important assumption of parametric statistical tests because they are sensitive to any dissimilarities. Uneven variances in samples result in biased and skewed test results.
What is variance used for in statistics?: Statistical tests such as variance tests or the analysis of variance (ANOVA) use sample variance to assess group differences of populations. They use the variances of the samples to assess whether the populations they come from significantly differ from each other.
Can I stratify by multiple characteristics at once?: Yes, you can create a stratified sample using multiple characteristics, but you must ensure that every participant in your study belongs to one and only one subgroup. In this case, you multiply the numbers of subgroups for each characteristic to get the total number of groups.

For example, if you were stratifying by location with three subgroups (urban, rural, or suburban) and marital status with five subgroups (single, divorced, widowed, married, or partnered), you would have 3 x 5 = 15 subgroups.
When should I use stratified sampling?: You should use stratified sampling when your sample can be divided into mutually exclusive and exhaustive subgroups that you believe will take on different mean values for the variable that you’re studying.

Using stratified sampling will allow you to obtain more precise (with lower variance) statistical estimates of whatever you are trying to measure.

For example, say you want to investigate how income differs based on educational attainment, but you know that this relationship can vary based on race. Using stratified sampling, you can ensure you obtain a large enough sample from each racial group, allowing you to draw more precise conclusions.
What is stratified sampling?: In stratified sampling, researchers divide subjects into subgroups called strata based on characteristics that they share (e.g., race, gender, educational attainment, etc).

Once divided, each subgroup is randomly sampled using another probability sampling method.
Why do I need a thesis statement?: The thesis statement is essential in any academic essay or research paper for two main reasons:

It gives your writing direction and focus.

It gives the reader a concise summary of your main point.

Without a clear thesis, an essay can end up rambling and unfocused, leaving your reader unsure of exactly what you want to say.
Where does the thesis statement go in an essay?: The thesis statement should be placed at the end of your essay introduction.
How can I come up with a thesis statement?: Follow these three steps to come up with a thesis:

Ask a question about your topic.

Write your initial answer.

Develop your answer and include reasons.
What is a thesis statement?: A thesis statement is a sentence that sums up the central point of your paper or essay. Everything else you write should relate to this key idea.
Why is structure important in an essay?: An essay isn’t just a loose collection of facts and ideas. Instead, it should be centered on an overarching argument (summarized in your thesis statement) that every part of the essay relates to.

The way you structure your essay is crucial to presenting your argument coherently. A well-structured essay helps your reader follow the logic of your ideas and understand your overall point.
What is the structure of an essay?: The structure of an essay is divided into an introduction that presents your topic and thesis statement, a body containing your in-depth analysis and arguments, and a conclusion wrapping up your ideas.

The structure of the body is flexible, but you should always spend some time thinking about how you can organize your essay to best serve your ideas.
What’s the difference between standard deviation and variance?: Variance is the average squared deviations from the mean, while standard deviation is the square root of this number. Both measures reflect variability in a distribution, but their units differ:

Standard deviation is expressed in the same units as the original values (e.g., minutes or meters).

Variance is expressed in much larger units (e.g., meters squared).

Although the units of variance are harder to intuitively understand, variance is important in statistical tests.
What is the empirical rule?: The empirical rule, or the 68-95-99.7 rule, tells you where most of the values lie in a normal distribution:

Around 68% of values are within 1 standard deviation of the mean.

Around 95% of values are within 2 standard deviations of the mean.

Around 99.7% of values are within 3 standard deviations of the mean.

The empirical rule is a quick way to get an overview of your data and check for any outliers or extreme values that don’t follow this pattern.
What is a normal distribution?: In a normal distribution, data is symmetrically distributed with no skew. Most values cluster around a central region, with values tapering off as they go further away from the center.

The measures of central tendency (mean, mode and median) are exactly the same in a normal distribution.
What does standard deviation tell you?: The standard deviation is the average amount of variability in your data set. It tells you, on average, how far each score lies from the mean.

In normal distributions, a high standard deviation means that values are generally far from the mean, while a low standard deviation indicates that values are clustered close to the mean.
What’s the difference between the discussion and the conclusion?: In a thesis or dissertation, the discussion is an in-depth exploration of the results, going into detail about the meaning of your findings and citing relevant sources to put them in context.

The conclusion is more shorter and more general: it concisely answers your main research question and makes recommendations based on your overall findings.
What goes in the discussion chapter of a dissertation?: In the discussion, you explore the meaning and relevance of your research results, explaining how they fit with existing research and theory. Discuss:

Your interpretations: what do the results tell us?

The implications: why do the results matter?

The limitations: what can’t the results tell us?
What’s the difference between results and discussion?: The results chapter or section simply and objectively reports what you found, without speculating on why you found these results. The discussion interprets the meaning of the results, puts them in context, and explains why they matter.

In qualitative research, results and discussion are sometimes combined. But in quantitative research, it’s considered important to separate the objective results from your interpretation of them.
What tense should I write my results in?: Results are usually written in the past tense, because they are describing the outcome of completed actions.
What goes in the results chapter of a dissertation?: The results chapter of a thesis or dissertation presents your research results concisely and objectively.

In quantitative research, for each question or hypothesis, state:

The type of analysis used

Relevant results in the form of descriptive and inferential statistics

Whether or not the hypothesis was supported

In qualitative research, for each question or theme, describe:

Recurring patterns

Significant or representative individual responses

Relevant quotations from the data

Don’t interpret or speculate in the results chapter.
Can the range be a negative number?: No. Because the range formula subtracts the lowest number from the highest number, the range is always zero or a positive number.
What is the range in statistics?: In statistics, the range is the spread of your data from the lowest to the highest value in the distribution. It is the simplest measure of variability.
What are some advantages and disadvantages of cluster sampling?: Cluster sampling is more time- and cost-efficient than other probability sampling methods, particularly when it comes to large samples spread across a wide geographical area.

However, it provides less statistical certainty than other methods, such as simple random sampling, because it is difficult to ensure that your clusters properly represent the population as a whole.
What are the types of cluster sampling?: There are three types of cluster sampling: single-stage, double-stage and multi-stage clustering. In all three types, you first divide the population into clusters, then randomly select clusters for use in your sample.

In single-stage sampling, you collect data from every unit within the selected clusters.

In double-stage sampling, you select a random sample of units from within the clusters.

In multi-stage sampling, you repeat the procedure of randomly sampling elements from within the clusters until you have reached a manageable sample size.
What is cluster sampling?: Cluster sampling is a probability sampling method in which you divide a population into clusters, such as districts or schools, and then randomly select some of these clusters as your sample.

The clusters should ideally each be mini-representations of the population as a whole.
What’s the difference between central tendency and variability?: While central tendency tells you where most of your data points lie, variability summarizes how far apart your points from each other.

Data sets can have the same central tendency but different levels of variability or vice versa. Together, they give you a complete picture of your data.
What are the 4 main measures of variability?: Variability is most commonly measured with the following descriptive statistics:

Range: the difference between the highest and lowest values

Interquartile range: the range of the middle half of a distribution

Standard deviation: average distance from the mean

Variance: average of squared distances from the mean
What is variability?: Variability tells you how far apart points lie from each other and from the center of a distribution or a data set.

Variability is also referred to as spread, scatter or dispersion.
What type of essay is most common at university?: The vast majority of essays written at university are some sort of argumentative essay. Almost all academic writing involves building up an argument, though other types of essay might be assigned in composition classes.

Essays can present arguments about all kinds of different topics. For example:

In a literary analysis essay, you might make an argument for a specific interpretation of a text

In a history essay, you might present an argument for the importance of a particular event

In a politics essay, you might argue for the validity of a certain political theory
How do I know what type of essay to write?: At high school and in composition classes at university, you’ll often be told to write a specific type of essay, but you might also just be given prompts.

Look for keywords in these prompts that suggest a certain approach: The word “explain” suggests you should write an expository essay, while the word “describe” implies a descriptive essay. An argumentative essay might be prompted with the word “assess” or “argue.”
What is the difference between interval and ratio data?: While interval and ratio data can both be categorized, ranked, and have equal spacing between adjacent values, only ratio scales have a true zero.

For example, temperature in Celsius or Fahrenheit is at an interval scale because zero is not the lowest possible temperature. In the Kelvin scale, a ratio scale, zero represents a total lack of thermal energy.
What are claims, supports, and warrants?: In rhetorical analysis, a claim is something the author wants the audience to believe. A support is the evidence or appeal they use to convince the reader to believe the claim. A warrant is the (often implicit) assumption that links the support with the claim.
What are logos, ethos, and pathos?: Logos appeals to the audience’s reason, building up logical arguments. Ethos appeals to the speaker’s status or authority, making the audience more likely to trust them. Pathos appeals to the emotions, trying to make the audience feel angry or sympathetic, for example.

Collectively, these three appeals are sometimes called the rhetorical triangle. They are central to rhetorical analysis, though a piece of rhetoric might not necessarily use all of them.
What counts as a text for rhetorical analysis?: The term “text” in a rhetorical analysis essay refers to whatever object you’re analyzing. It’s frequently a piece of writing or a speech, but it doesn’t have to be. For example, you could also treat an advertisement or political cartoon as a text.
What’s the goal of a rhetorical analysis?: The goal of a rhetorical analysis is to explain the effect a piece of writing or oratory has on its audience, how successful it is, and the devices and appeals it uses to achieve its goals.

Unlike a standard argumentative essay, it’s less about taking a position on the arguments presented, and more about exploring how they are constructed.
What is a critical value?: A critical value is the value of the test statistic which defines the upper and lower bounds of a confidence interval, or which defines the threshold of statistical significance in a statistical test. It describes how far from the mean of the distribution you have to go to cover a certain amount of the total variation in the data (i.e. 90%, 95%, 99%).

If you are constructing a 95% confidence interval and are using a threshold of statistical significance of p = 0.05, then your critical value will be identical in both cases.
What is the difference between the t-distribution and the standard normal distribution?: The t-distribution gives more probability to observations in the tails of the distribution than the standard normal distribution (a.k.a. the z-distribution).

In this way, the t-distribution is more conservative than the standard normal distribution: to reach the same level of confidence or statistical significance, you will need to include a wider range of the data.
What is a t-score?: A t-score (a.k.a. a t-value) is equivalent to the number of standard deviations away from the mean of the t-distribution.

The t-score is the test statistic used in t-tests and regression tests. It can also be used to describe how far from the mean an observation is when the data follow a t-distribution.
What is a t-distribution?: The t-distribution is a way of describing a set of observations where most observations fall close to the mean, and the rest of the observations make up the tails on either side. It is a type of normal distribution used for smaller sample sizes, where the variance in the data is unknown.

The t-distribution forms a bell curve when plotted on a graph. It can be described mathematically using the mean and the standard deviation.
When should I use simple random sampling?: If properly implemented, simple random sampling is usually the best sampling method for ensuring both internal and external validity. However, it can sometimes be impractical and expensive to implement, depending on the size of the population to be studied,

If you have a list of every member of the population and the ability to reach whichever members are selected, you can use simple random sampling.
What is an example of simple random sampling?: The American Community Survey is an example of simple random sampling. In order to collect detailed data on the population of the US, the Census Bureau officials randomly select 3.5 million households per year and use a variety of methods to convince them to fill out the survey.
What is simple random sampling?: Simple random sampling is a type of probability sampling in which the researcher randomly selects a subset of participants from a population. Each member of the population has an equal chance of being selected. Data is then collected from as large a percentage as possible of this random subset.
Do I have to stick to my essay outline as I write?: You should try to follow your outline as you write your essay. However, if your ideas change or it becomes clear that your structure could be better, it’s okay to depart from your essay outline. Just make sure you know why you’re doing so.
Should I use full sentences in my essay outline?: If you have to hand in your essay outline, you may be given specific guidelines stating whether you have to use full sentences. If you’re not sure, ask your supervisor.

When writing an essay outline for yourself, the choice is yours. Some students find it helpful to write out their ideas in full sentences, while others prefer to summarize them in short phrases.
When do I need to write an essay outline?: You will sometimes be asked to hand in an essay outline before you start writing your essay. Your supervisor wants to see that you have a clear idea of your structure so that writing will go smoothly.

Even when you do not have to hand it in, writing an essay outline is an important part of the writing process. It’s a good idea to write one (as informally as you like) to clarify your structure for yourself whenever you are working on an essay.
Are ordinal variables categorical or quantitative?: In statistics, ordinal and nominal variables are both considered categorical variables.

Even though ordinal data can sometimes be numerical, not all mathematical operations can be performed on them.
What is ordinal data?: Ordinal data has two characteristics:

The data can be classified into different categories within a variable.

The categories have a natural ranked order.

However, unlike with interval data, the distances between the categories are uneven or unknown.
How do I create a table of contents?: To automatically insert a table of contents in Microsoft Word, follow these steps:

Apply heading styles throughout the document.

In the references section in the ribbon, locate the Table of Contents group.

Click the arrow next to the Table of Contents icon and select Custom Table of Contents.

Select which levels of headings you would like to include in the table of contents.

Click OK.

Make sure to update your table of contents if you move text or change headings. To update, simply right click and select Update Field.
What should be included in a dissertation table of contents?: All level one and two headings should be included in your table of contents. That means the titles of your chapters and the main sections within them.

The contents should also include all appendices and the lists of tables and figures, if applicable, as well as your reference list.

Do not include the acknowledgements or abstract in the table of contents.
What’s the difference between nominal and ordinal data?: Nominal and ordinal are two of the four levels of measurement. Nominal level data can only be classified, while ordinal level data can be classified and ordered.
What is nominal data?: Nominal data is data that can be labelled or classified into mutually exclusive categories within a variable. These categories cannot be ordered in a meaningful way.

For example, for the nominal variable of preferred mode of transportation, you may have the categories of car, bus, train, tram or bicycle.
What does it mean if my confidence interval includes zero?: If your confidence interval for a difference between groups includes zero, that means that if you run your experiment again you have a good chance of finding no difference between groups.

If your confidence interval for a correlation or regression includes zero, that means that if you run your experiment again there is a good chance of finding no correlation in your data.

In both of these cases, you will also find a high p-value when you run your statistical test, meaning that your results could have occurred under the null hypothesis of no relationship between variables or no difference between groups.
How do I calculate a confidence interval if my data are not normally distributed?: If you want to calculate a confidence interval around the mean of data that is not normally distributed, you have two choices:

Find a distribution that matches the shape of your data and use that distribution to calculate the confidence interval.

Perform a transformation on your data to make it fit a normal distribution, and then find the confidence interval for the transformed data.
What is a standard normal distribution?: The standard normal distribution, also called the z-distribution, is a special normal distribution where the mean is 0 and the standard deviation is 1.

Any normal distribution can be converted into the standard normal distribution by turning the individual values into z-scores. In a z-distribution, z-scores tell you how many standard deviations away from the mean each value lies.
What are z-scores and t-scores?: The z-score and t-score (aka z-value and t-value) show how many standard deviations away from the mean of the distribution you are, assuming your data follow a z-distribution or a t-distribution.

These scores are used in statistical tests to show how far from the mean of the predicted distribution your statistical estimate is. If your test produces a z-score of 2.5, this means that your estimate is 2.5 standard deviations from the predicted mean.

The predicted mean and distribution of your estimate are generated by the null hypothesis of the statistical test you are using. The more standard deviations away from the predicted mean your estimate is, the less likely it is that the estimate could have occurred under the null hypothesis.
How do you calculate a confidence interval?: To calculate the confidence interval, you need to know:

The point estimate you are constructing the confidence interval for

The critical values for the test statistic

The standard deviation of the sample

The sample size

Then you can plug these components into the confidence interval formula that corresponds to your data. The formula depends on the type of estimate (e.g. a mean or a proportion) and on the distribution of your data.
What is the difference between a confidence interval and a confidence level?: The confidence level is the percentage of times you expect to get close to the same estimate if you run your experiment again or resample the population in the same way.

The confidence interval is the actual upper and lower bounds of the estimate you expect to find at a given level of confidence.

For example, if you are estimating a 95% confidence interval around the mean proportion of female babies born every year based on a random sample of babies, you might find an upper bound of 0.56 and a lower bound of 0.48. These are the upper and lower bounds of the confidence interval. The confidence level is 95%.

This means that 95% of the time, you can expect your estimate to fall between 0.56 and 0.48.
Where does the abstract go in a thesis or dissertation?: The abstract appears on its own page, after the title page and acknowledgements but before the table of contents.
When should I write the abstract?: The abstract is the very last thing you write. You should only write it after your research is complete, so that you can accurately summarize the entirety of your thesis or paper.
How long is a dissertation abstract?: An abstract for a thesis or dissertation is usually around 200–300 words. There’s often a strict word limit, so make sure to check your university’s requirements.
How long should the acknowledgements be?: In a thesis or dissertation, the acknowledgements should usually be no longer than one page. There is no minimum length.
Where do the acknowledgements go in a thesis or dissertation?: The acknowledgements are generally included at the very beginning of your thesis, directly after the title page and before the abstract.
Do I have to thank my supervisor?: Yes, it’s important to thank your supervisor(s) in the acknowledgements section of your thesis or dissertation. Even if they were not heavily involved, it’s important to at least briefly acknowledge their assistance.
Who should I thank in the acknowledgements?: In the acknowledgements of your thesis or dissertation, you should first thank those who helped you academically or professionally, such as your supervisor, funders, and other academics.

Then you can include personal thanks to friends, family members, or anyone else who supported you during the process.
How do I compare and contrast in a structured way?: Comparisons in essays are generally structured in one of two ways:

The alternating method, where you compare your subjects side by side according to one specific aspect at a time.

The block method, where you cover each subject separately in its entirety.

It’s also possible to combine both methods, for example by writing a full paragraph on each of your topics and then a final paragraph contrasting the two according to a specific metric.
How do I choose subjects to compare and contrast?: Your subjects might be very different or quite similar, but it’s important that there be meaningful grounds for comparison. You can probably describe many differences between a cat and a bicycle, but there isn’t really any connection between them to justify the comparison.

You’ll have to write a thesis statement explaining the central point you want to make in your essay, so be sure to know in advance what connects your subjects and makes them worth comparing.
When do I need to compare and contrast?: Some essay prompts include the keywords “compare” and/or “contrast.” In these cases, an essay structured around comparing and contrasting is the appropriate response.

Comparing and contrasting is also a useful approach in all kinds of academic writing: You might compare different studies in a literature review, weigh up different arguments in an argumentative essay, or consider different theoretical approaches in a theoretical framework.
When should I use a quasi-experimental design?: Quasi-experimental design is most useful in situations where it would be unethical or impractical to run a true experiment.

Quasi-experiments have lower internal validity than true experiments, but they often have higher external validity as they can use real-world interventions instead of artificial laboratory settings.
What is a quasi-experiment?: A quasi-experiment is a type of research design that attempts to establish a cause-and-effect relationship. The main difference with a true experiment is that the groups are not randomly assigned.
What’s the difference between a narrative essay and a descriptive essay?: The key difference is that a narrative essay is designed to tell a complete story, while a descriptive essay is meant to convey an intense description of a particular place, object, or concept.

Narrative and descriptive essays both allow you to write more personally and creatively than other kinds of essays, and similar writing skills can apply to both.
How do I come up with a topic for my descriptive essay?: If you’re not given a specific prompt for your descriptive essay, think about places and objects you know well, that you can think of interesting ways to describe, or that have strong personal significance for you.

The best kind of object for a descriptive essay is one specific enough that you can describe its particular features in detail—don’t choose something too vague or general.
What’s the best measure of central tendency to use?: The mean is the most frequently used measure of central tendency because it uses all values in the data set to give you an average.

For data from skewed distributions, the median is better than the mean because it isn’t influenced by extremely large values.

The mode is the only measure you can use for nominal or categorical data that can’t be ordered.
Which measures of central tendency can I use?: The measures of central tendency you can use depends on the level of measurement of your data.

For a nominal level, you can only use the mode to find the most frequent value.

For an ordinal level or ranked data, you can also use the median to find the value in the middle of your data set.

For interval or ratio levels, in addition to the mode and median, you can use the mean to find the average value.
What are measures of central tendency?: Measures of central tendency help you find the middle, or the average, of a data set.

The 3 most common measures of central tendency are the mean, median and mode.

The mode is the most frequent value.

The median is the middle number in an ordered data set.

The mean is the sum of all values divided by the total number of values.
How do I come up with a topic for my narrative essay?: If you’re not given much guidance on what your narrative essay should be about, consider the context and scope of the assignment. What kind of story is relevant, interesting, and possible to tell within the word count?

The best kind of story for a narrative essay is one you can use to reflect on a particular theme or lesson, or that takes a surprising turn somewhere along the way.

Don’t worry too much if your topic seems unoriginal. The point of a narrative essay is how you tell the story and the point you make with it, not the subject of the story itself.
When do I write a narrative essay?: Narrative essays are usually assigned as writing exercises at high school or in university composition classes. They may also form part of a university application.

When you are prompted to tell a story about your own life or experiences, a narrative essay is usually the right response.
When do I write an argumentative essay?: The majority of the essays written at university are some sort of argumentative essay. Unless otherwise specified, you can assume that the goal of any essay you’re asked to write is argumentative: To convince the reader of your position using evidence and reasoning.

In composition classes you might be given assignments that specifically test your ability to write an argumentative essay. Look out for prompts including instructions like “argue,” “assess,” or “discuss” to see if this is the goal.
When do I need to cite sources?: At college level, you must properly cite your sources in all essays, research papers, and other academic texts (except exams and in-class exercises).

Add a citation whenever you quote, paraphrase, or summarize information or ideas from a source. You should also give full source details in a bibliography or reference list at the end of your text.

The exact format of your citations depends on which citation style you are instructed to use. The most common styles are APA, MLA, and Chicago.
How do I decide which level of measurement to use?: Some variables have fixed levels. For example, gender and ethnicity are always nominal level data because they cannot be ranked.

However, for other variables, you can choose the level of measurement. For example, income is a variable that can be recorded on an ordinal or a ratio scale:

At an ordinal level, you could create 5 income groupings and code the incomes that fall within them from 1–5.

At a ratio level, you would record exact numbers for income.

If you have a choice, the ratio level is always preferable because you can analyze data in more ways. The higher the level of measurement, the more precise your data is.
Why do levels of measurement matter?: The level at which you measure a variable determines how you can analyze your data.

Depending on the level of measurement, you can perform different descriptive statistics to get an overall summary of your data and inferential statistics to see if your results support or refute your hypothesis.
What are the four levels of measurement?: Levels of measurement tell you how precisely variables are recorded. There are 4 levels of measurement, which can be ranked from low to high:

Nominal: the data can only be categorized.

Ordinal: the data can be categorized and ranked.

Interval: the data can be categorized and ranked, and evenly spaced.

Ratio: the data can be categorized, ranked, evenly spaced and has a natural zero.
Does a p-value tell you whether your alternative hypothesis is true?: No. The p-value only tells you how likely the data you have observed is to have occurred under the null hypothesis.

If the p-value is below your threshold of significance (typically p < 0.05), then you can reject the null hypothesis, but this does not necessarily mean that your alternative hypothesis is true.
Which alpha value should I use?: The alpha value, or the threshold for statistical significance, is arbitrary – which value you use depends on your field of study.

In most cases, researchers use an alpha of 0.05, which means that there is a less than 5% chance that the data being tested could have occurred under the null hypothesis.
How do you calculate a p-value?: P-values are usually automatically calculated by the program you use to perform your statistical test. They can also be estimated using p-value tables for the relevant test statistic.

P-values are calculated from the null distribution of the test statistic. They tell you how often a test statistic is expected to occur under the null hypothesis of the statistical test, based on where it falls in the null distribution.

If the test statistic is far from the mean of the null distribution, then the p-value will be small, showing that the test statistic is not likely to have occurred under the null hypothesis.
What is a p-value?: A p-value, or probability value, is a number describing how likely it is that your data would have occurred under the null hypothesis of your statistical test.
How do I know which test statistic to use?: The test statistic you use will be determined by the statistical test.

You can choose the right statistical test by looking at what type of data you have collected and what type of relationship you want to test.
What factors affect the test statistic?: The test statistic will change based on the number of observations in your data, how variable your observations are, and how strong the underlying patterns in the data are.

For example, if one data set has higher variability while another has lower variability, the first data set will produce a test statistic closer to the null hypothesis, even if the true correlation between two variables is the same in either data set.
How do you calculate a test statistic?: The formula for the test statistic depends on the statistical test being used.

Generally, the test statistic is calculated as the pattern in your data (i.e. the correlation between variables or difference between groups) divided by the variance in the data (i.e. the standard deviation).
What’s the difference between an expository essay and an argumentative essay?: An argumentative essay tends to be a longer essay involving independent research, and aims to make an original argument about a topic. Its thesis statement makes a contentious claim that must be supported in an objective, evidence-based way.

An expository essay also aims to be objective, but it doesn’t have to make an original argument. Rather, it aims to explain something (e.g., a process or idea) in a clear, concise way. Expository essays are often shorter assignments and rely less on research.
When do I write an expository essay?: An expository essay is a common assignment in high-school and university composition classes. It might be assigned as coursework, in class, or as part of an exam.

Sometimes you might not be told explicitly to write an expository essay. Look out for prompts containing keywords like “explain” and “define.” An expository essay is usually the right response to these prompts.
How long is an expository essay?: An expository essay is a broad form that varies in length according to the scope of the assignment.

Expository essays are often assigned as a writing exercise or as part of an exam, in which case a five-paragraph essay of around 800 words may be appropriate.

You’ll usually be given guidelines regarding length; if you’re not sure, ask.
Why is blinding important?: Blinding is important to reduce bias and ensure a study’s internal validity.

If participants know whether they are in a control or treatment group, they may adjust their behavior in ways that affect the outcome that researchers are trying to measure. If the people administering the treatment are aware of group assignment, they may treat participants differently and thus directly or indirectly influence the final results.
What is the difference between single-blind, double-blind and triple-blind studies?: In a single-blind study, only the participants are blinded.

In a double-blind study, both participants and experimenters are blinded.

In a triple-blind study, the assignment is hidden not only from participants and experimenters, but also from the researchers analyzing the data.
What is blinding?: Blinding means hiding who is assigned to the treatment group and who is assigned to the control group in an experiment.
What’s the difference between univariate, bivariate and multivariate descriptive statistics?: Univariate statistics summarize only one variable at a time.

Bivariate statistics compare two variables.

Multivariate statistics compare more than two variables.
What are the 3 main types of descriptive statistics?: The 3 main types of descriptive statistics concern the frequency distribution, central tendency, and variability of a dataset.

Distribution refers to the frequencies of different responses.

Measures of central tendency give you the average for each response.

Measures of variability show you the spread or dispersion of your dataset.
What’s the difference between descriptive and inferential statistics?: Descriptive statistics summarize the characteristics of a data set. Inferential statistics allow you to test a hypothesis or assess whether your data is generalizable to the broader population.
Do experiments always need a control group?: A true experiment (a.k.a. a controlled experiment) always includes at least one control group that doesn’t receive the experimental treatment.

However, some experiments use a within-subjects design to test treatments without a control group. In these designs, you usually compare one group’s outcomes before and after a treatment (instead of comparing outcomes between different groups).

For strong internal validity, it’s usually best to include a control group if possible. Without a control group, it’s harder to be certain that the outcome was caused by the experimental treatment and not by other variables.
What is the difference between a control group and an experimental group?: An experimental group, also known as a treatment group, receives the treatment whose effect researchers wish to study, whereas a control group does not. They should be identical in all other ways.
Are Likert scales ordinal or interval scales?: Individual Likert-type questions are generally considered ordinal data, because the items have clear rank order, but don’t have an even distribution.

Overall Likert scale scores are sometimes treated as interval data. These scores are considered to have directionality and even spacing between them.

The type of data determines what statistical tests you should use to analyze your data.
What is a Likert scale?: A Likert scale is a rating scale that quantitatively assesses opinions, attitudes, or behaviors. It is made up of 4 or more questions that measure a single attitude or trait when response scores are combined.

To use a Likert scale in a survey, you present participants with Likert-type questions or statements, and a continuum of items, usually with 5 or 7 possible responses, to capture their degree of agreement.
How do I cite a source with multiple authors in Chicago style?: In a Chicago style footnote, list up to three authors. If there are more than three, name only the first author, followed by “et al.”

In the bibliography, list up to 10 authors. If there are more than 10, list the first seven followed by “et al.”

Full note Short note Bibliography

2 authors Anna Burns and Robert Smith Burns and Smith Burns, Anna, and Robert Smith.

3 authors Anna Burns, Robert Smith, and Judith Green Burns, Smith, and Green Burns, Anna, Robert Smith, and Judith Green.

4+ authors Anna Burns et al. Burns et al. Burns, Anna, Robert Smith, Judith Green, and Maggie White.

The same rules apply in Chicago author-date style.
What’s the difference between concepts, variables, and indicators?: In scientific research, concepts are the abstract ideas or phenomena that are being studied (e.g., educational achievement). Variables are properties or characteristics of the concept (e.g., performance at school), while indicators are ways of measuring or quantifying variables (e.g., yearly grade reports).

The process of turning abstract concepts into measurable variables and indicators is called operationalization.
How do you analyze qualitative data?: There are various approaches to qualitative data analysis, but they all share five steps in common:

Prepare and organize your data.

Review and explore your data.

Develop a data coding system.

Assign codes to the data.

Identify recurring themes.

The specifics of each step depend on the focus of the analysis. Some common approaches include textual analysis, thematic analysis, and discourse analysis.
What are the main qualitative research approaches?: There are five common approaches to qualitative research:

Grounded theory involves collecting data in order to develop new theories.

Ethnography involves immersing yourself in a group or organization to understand its culture.

Narrative research involves interpreting stories to understand how people make sense of their experiences and perceptions.

Phenomenological research involves investigating phenomena through people’s lived experiences.

Action research links theory and practice in several cycles to drive innovative changes.
What is hypothesis testing?: Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses, by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.
How do I cite a source with no date in Chicago style?: When an online source does not list a publication date, replace it with an access date in your in footnote citations and your bibliography:

Example: Chicago bibliography entry with access date
Scribbr. “How to Write a Research Paper.” Accessed June 9, 2020. https://www.scribbr.com/category/research-paper/.

If you are using author-date in-text citations, or if the source was not accessed online, replace the date with “n.d.”

Example: Chicago author-date citation with no date
(Scribbr, n.d.)
How do I cite a source with no author in Chicago style?: In a Chicago footnote citation, when the author of a source is unknown (as is often the case with websites), start the citation with the title in a full note. In short notes and bibliography entries, list the organization that published it as the author.

Type Example

Full note 1. “An Introduction to Research Methods,” Scribbr, accessed June 11, 2020, https://www.scribbr.com/category/methodology/.

Short note 2. Scribbr, “Research Methods.”

Bibliography Scribbr. “An Introduction to Research Methods.” Accessed June 11, 2020. https://www.scribbr.com/category/methodology/.

In Chicago author-date style, treat the organization as author in your in-text citations and reference list.
What is operationalization?: Operationalization means turning abstract conceptual ideas into measurable observations.

For example, the concept of social anxiety isn’t directly observable, but it can be operationally defined in terms of self-rating scores, behavioral avoidance of crowded places, or physical anxiety symptoms in social situations.

Before collecting data, it’s important to consider how you will operationalize the variables that you want to measure.
What are the benefits of collecting data?: When conducting research, collecting original data has significant advantages:

You can tailor data collection to your specific research aims (e.g. understanding the needs of your consumers or user testing your website)

You can control and standardize the process for high reliability and validity (e.g. choosing appropriate measurements and sampling methods)

However, there are also some drawbacks: data collection can be time-consuming, labor-intensive and expensive. In some cases, it’s more efficient to use secondary data that has already been collected by someone else, but the data might be less reliable.
What is data collection?: Data collection is the systematic process by which observations or measurements are gathered in research. It is used in many different contexts by academics, governments, businesses, and other organizations.
How do I prevent confounding variables from interfering with my research?: There are several methods you can use to decrease the impact of confounding variables on your research: restriction, matching, statistical control and randomization.

In restriction, you restrict your sample by only including certain subjects that have the same values of potential confounding variables.

In matching, you match each of the subjects in your treatment group with a counterpart in the comparison group. The matched subjects have the same values on any potential confounding variables, and only differ in the independent variable.

In statistical control, you include potential confounders as variables in your regression.

In randomization, you randomly assign the treatment (or independent variable) in your study to a sufficiently large number of subjects, which allows you to control for all potential confounding variables.
What is the difference between confounding variables, independent variables and dependent variables?: A confounding variable is closely related to both the independent and dependent variables in a study. An independent variable represents the supposed cause, while the dependent variable is the supposed effect. A confounding variable is a third variable that influences both the independent and dependent variables.

Failing to account for confounding variables can cause you to wrongly estimate the relationship between your independent and dependent variables.
Why do confounding variables matter for my research?: To ensure the internal validity of your research, you must consider the impact of confounding variables. If you fail to account for them, you might over- or underestimate the causal relationship between your independent and dependent variables, or even find a causal relationship where none exists.
Can I include more than one independent or dependent variable in a study?: Yes, but including more than one of either type requires multiple research questions.

For example, if you are interested in the effect of a diet on health, you can use multiple measures of health: blood sugar, blood pressure, weight, pulse, and many more. Each of these is its own dependent variable with its own research question.

You could also choose to look at the effect of exercise levels as well as diet, or even the additional effect of the two combined. Each of these is a separate independent variable.

To ensure the internal validity of an experiment, you should only change one independent variable at a time.
Can a variable be both independent and dependent?: No. The value of a dependent variable depends on an independent variable, so a variable cannot be both independent and dependent at the same time. It must be either the cause or the effect, not both!
What is an example of an independent and a dependent variable?: You want to find out how blood sugar levels are affected by drinking diet soda and regular soda, so you conduct an experiment.

The type of soda – diet or regular – is the independent variable.

The level of blood sugar that you measure is the dependent variable – it changes depending on the type of soda.
Why are independent and dependent variables important?: Determining cause and effect is one of the most important parts of scientific research. It’s essential to know which is the cause – the independent variable – and which is the effect – the dependent variable.
What is non-probability sampling?: In non-probability sampling, the sample is selected based on non-random criteria, and not every member of the population has a chance of being included.

Common non-probability sampling methods include convenience sampling, voluntary response sampling, purposive sampling, snowball sampling, and quota sampling.
What is probability sampling?: Probability sampling means that every member of the target population has a known chance of being included in the sample.

Probability sampling methods include simple random sampling, systematic sampling, stratified sampling, and cluster sampling.
How do you avoid sampling bias?: Using careful research design and sampling procedures can help you avoid sampling bias. Oversampling can be used to correct undercoverage bias.
What are some types of sampling bias?: Some common types of sampling bias include self-selection, non-response, undercoverage, survivorship, pre-screening or advertising, and healthy user bias.
Why is sampling bias important?: Sampling bias is a threat to external validity – it limits the generalizability of your findings to a broader group of people.
What is sampling bias?: Sampling bias occurs when some members of a population are systematically more likely to be selected in a sample than others.
What is sampling error?: A sampling error is the difference between a population parameter and a sample statistic.
What’s the difference between a statistic and a parameter?: A statistic refers to measures about the sample, while a parameter refers to measures about the population.
When are populations used in research?: Populations are used when a research question requires data from every member of the population. This is usually only feasible when the population is small and easily accessible.
Why are samples used in research?: Samples are used to make inferences about populations. Samples are easier to collect data from because they are practical, cost-effective, convenient and manageable.
How do I cite a source with no author or page numbers in MLA?: If a source has no author, start the MLA Works Cited entry with the source title. Use a shortened version of the title in your in-text citation.

If a source has no page numbers, you can use an alternative locator (e.g. a chapter number, or a timestamp for a video or audio source) to identify the relevant passage in your in-text citation. If the source has no numbered divisions, cite only the author’s name (or the title).

If you already named the author or title in your sentence, and there is no locator available, you don’t need a parenthetical citation:

Rajaram argues that representations of migration are shaped by “cultural, political, and ideological interests.”

The homepage of The Correspondent describes it as “a movement for radically different news.”
How do I cite a source with multiple authors in MLA?: In MLA Style, if a source has two authors, name both authors in your in-text citation and Works Cited entry. If there are three or more authors, name only the first author, followed by et al.

Number of authors In-text citation Works Cited entry

1 author (Moore 37) Moore, Jason W.

2 authors (Moore and Patel 37) Moore, Jason W., and Raj Patel.

3+ authors (Moore et al. 37) Moore, Jason W., et al.
When do I need to include an MLA in-text citation?: You must include an in-text citation every time you quote or paraphrase from a source (e.g. a book, movie, website, or article).
What are threats to external validity?: There are seven threats to external validity: selection bias, history, experimenter effect, Hawthorne effect, testing effect, aptitude-treatment and situation effect.
What are the two types of external validity?: The two types of external validity are population validity (whether you can generalize to other groups of people) and ecological validity (whether you can generalize to other situations and settings).
What is external validity?: The external validity of a study is the extent to which you can generalize your findings to different groups of people, situations, and measures.
What are the disadvantages of a cross-sectional study?: Cross-sectional studies cannot establish a cause-and-effect relationship or analyze behavior over a period of time. To investigate cause and effect, you need to do a longitudinal study or an experimental study.
Why do a cross-sectional study?: Cross-sectional studies are less expensive and time-consuming than many other types of study. They can provide useful insights into a population’s characteristics and identify correlations for further research.

Sometimes only cross-sectional data is available for analysis; other times your research question may only require a cross-sectional study to answer it.
How long is a longitudinal study?: Longitudinal studies can last anywhere from weeks to decades, although they tend to be at least a year long.
What is an example of a longitudinal study?: The 1970 British Cohort Study, which has collected data on the lives of 17,000 Brits since their births in 1970, is one well-known example of a longitudinal study.
What are the pros and cons of a longitudinal study?: Longitudinal studies are better to establish the correct sequence of events, identify changes over time, and provide insight into cause-and-effect relationships, but they also tend to be more expensive and time-consuming than other types of studies.
What is the difference between a longitudinal study and a cross-sectional study?: Longitudinal studies and cross-sectional studies are two different types of research design. In a cross-sectional study you collect data from a population at a specific point in time; in a longitudinal study you repeatedly collect data from the same sample over an extended period of time.

Longitudinal study Cross-sectional study

Repeated observations Observations at a single point in time

Observes the same group multiple times Observes different groups (a “cross-section”) in the population

Follows changes in participants over time Provides snapshot of society at a given point
What are threats to internal validity?: There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition.
What is internal validity?: Internal validity is the extent to which you can be confident that a cause-and-effect relationship established in a study cannot be explained by other factors.
How can I edit a paper that is over the word limit?: If you’ve gone over the word limit set for your assignment, shorten your sentences and cut repetition and redundancy during the editing process. If you use a lot of long quotes, consider shortening them to just the essentials.

If you need to remove a lot of words, you may have to cut certain passages. Remember that everything in the text should be there to support your argument; look for any information that’s not essential to your point and remove it.
What’s the difference between revising, proofreading, and editing?: Revising, proofreading, and editing are different stages of the writing process.

Revising is making structural and logical changes to your text—reformulating arguments and reordering information.

Editing refers to making more local changes to things like sentence structure and phrasing to make sure your meaning is conveyed clearly and concisely.

Proofreading involves looking at the text closely, line by line, to spot any typos and issues with consistency and correct them.
What is meant by model selection?: In statistics, model selection is a process researchers use to compare the relative value of different statistical models and determine which one is the best fit for the observed data.

The Akaike information criterion is one of the most common methods of model selection. AIC weights the ability of the model to predict the observed data against the number of parameters the model requires to reach that level of precision.

AIC model selection can help researchers find a model that explains the observed variation in their data while avoiding overfitting.
What is a model?: In statistics, a model is the collection of one or more independent variables and their predicted interactions that researchers use to try to explain variation in their dependent variable.

You can test a model using a statistical test. To compare how well different models fit your data, you can use Akaike’s information criterion for model selection.
How is AIC calculated?: The Akaike information criterion is calculated from the maximum log-likelihood of the model and the number of parameters (K) used to reach that likelihood. The AIC function is 2K – 2(log-likelihood).

Lower AIC values indicate a better-fit model, and a model with a delta-AIC (the difference between the two AIC values being compared) of more than -2 is considered significantly better than the model it is being compared to.
What is the Akaike information criterion?: The Akaike information criterion is a mathematical test used to evaluate how well a model fits the data it is meant to describe. It penalizes models which use more independent variables (parameters) as a way to avoid over-fitting.

AIC is most often used to compare the relative goodness-of-fit among different models under consideration and to then choose the model that best fits the data.
Should I include tables and figures in the reference list?: If you adapt or reproduce a table or figure from another source, you should include that source in your APA reference list. You should also acknowledge the original source in the note or caption for the table or figure.

Tables and figures you created yourself, based on your own data, are not included in the reference list.
Should I include lists of my tables and figures?: APA doesn’t require you to include a list of tables or a list of figures. However, it is advisable to do so if your text is long enough to feature a table of contents and it includes a lot of tables and/or figures.

A list of tables and list of figures appear (in that order) after your table of contents, and are presented in a similar way.
When should I use a table or figure to present data?: In an APA Style paper, use a table or figure when it’s a clearer way to present important data than describing it in your main text. This is often the case when you need to communicate a large amount of information.

Before including a table or figure in your text, always reflect on whether it’s useful to your readers’ understanding:

Could this information be quickly summarized in the text instead?

Is it important to your arguments?

Does the table or figure require too much explanation to be efficient?

If the data you need to present only contains a few relevant numbers, try summarizing it in the text (potentially including full data in an appendix). If describing the data makes your text overly long and difficult to read, a table or figure may be the best option.
What is a factorial ANOVA?: A factorial ANOVA is any ANOVA that uses more than one categorical independent variable. A two-way ANOVA is a type of factorial ANOVA.

Some examples of factorial ANOVAs include:

Testing the combined effects of vaccination (vaccinated or not vaccinated) and health status (healthy or pre-existing condition) on the rate of flu infection in a population.

Testing the effects of marital status (married, single, divorced, widowed), job status (employed, self-employed, unemployed, retired), and family history (no family history, some family history) on the incidence of depression in a population.

Testing the effects of feed type (type A, B, or C) and barn crowding (not crowded, somewhat crowded, very crowded) on the final weight of chickens in a commercial farming operation.
How is statistical significance calculated in an ANOVA?: In ANOVA, the null hypothesis is that there is no difference among group means. If any group differs significantly from the overall group mean, then the ANOVA will report a statistically significant result.

Significant differences among group means are calculated using the F statistic, which is the ratio of the mean sum of squares (the variance explained by the independent variable) to the mean square error (the variance left over).

If the F statistic is higher than the critical value (the value of F that corresponds with your alpha value, usually 0.05), then the difference among groups is deemed statistically significant.
What is the difference between a one-way and a two-way ANOVA?: The only difference between one-way and two-way ANOVA is the number of independent variables. A one-way ANOVA has one independent variable, while a two-way ANOVA has two.

One-way ANOVA: Testing the relationship between shoe brand (Nike, Adidas, Saucony, Hoka) and race finish times in a marathon.

Two-way ANOVA: Testing the relationship between shoe brand (Nike, Adidas, Saucony, Hoka), runner age group (junior, senior, master’s), and race finishing times in a marathon.

All ANOVAs are designed to test for differences among three or more groups. If you are only testing for a difference between two groups, use a t-test instead.
What is multiple linear regression?: Multiple linear regression is a regression model that estimates the relationship between a quantitative dependent variable and two or more independent variables using a straight line.
How is the error calculated in a linear regression model?: Linear regression most often uses mean-square error (MSE) to calculate the error of the model. MSE is calculated by:

measuring the distance of the observed y-values from the predicted y-values at each value of x;

squaring each of these distances;

calculating the mean of each of the squared distances.

Linear regression fits a line to the data by finding the regression coefficient that results in the smallest MSE.
What is simple linear regression?: Simple linear regression is a regression model that estimates the relationship between one independent variable and one dependent variable using a straight line. Both variables should be quantitative.

For example, the relationship between temperature and the expansion of mercury in a thermometer can be modeled using a straight line: as temperature increases, the mercury expands. This linear relationship is so certain that we can use mercury thermometers to measure temperature.
What is a regression model?: A regression model is a statistical model that estimates the relationship between one dependent variable and one or more independent variables using a line (or a plane in the case of two or more independent variables).

A regression model can be used when the dependent variable is quantitative, except in the case of logistic regression, where the dependent variable is binary.
Where does the literature review go in a dissertation?: The literature review usually comes near the beginning of your thesis or dissertation. After the introduction, it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology.
What is the purpose of a literature review?: There are several reasons to conduct a literature review at the beginning of a research project:

To familiarize yourself with the current state of knowledge on your topic

To ensure that you’re not just repeating what others have already done

To identify gaps in knowledge and unresolved problems that your research can address

To develop your theoretical framework and methodology

To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.
What is a literature review?: A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question.

It is often written as part of a thesis, dissertation, or research paper, in order to situate your work in relation to existing knowledge.
How should I organize a graduate school resume?: The sections in your graduate school resume depend on two things: your experience, and the focus of the program you’re applying to.

Always start with your education. If you have more than one degree, list the most recent one first.

The title and order of the other sections depend on what you want to emphasize. You might include things like:

Professional experience

Voluntary and extracurricular activities

Publications

Awards and honors

Skills and certifications

The resume should aim for a balance between two things: giving a snapshot of what you’ve done with your life so far, and showing that you’re a good candidate for graduate study.
What’s the difference between a resume and a CV?: A resume is typically shorter than a CV, giving only the most relevant professional and educational highlights.

An academic CV should give full details of your education and career, including lists of publications and presentations, certifications, memberships, grants, and research projects. Because it is more comprehensive, it’s acceptable for an academic CV to be many pages long.

Note that, outside of the US, resume and CV are often used interchangeably.
Should high school education be included in a grad school resume?: No, don’t include your high school courses and grades. The education section should only detail your college education.

If you want to discuss aspects of high school in your graduate school application, you can include this in your personal statement.
How long is a graduate school resume?: A resume for a graduate school application is typically no more than 1–2 pages long.

Note, however, that if you are asked to submit a CV (curriculum vitae), you should give comprehensive details of all your academic experience. An academic CV can be much longer than a normal resume.

Always carefully check the instructions and adhere to any length requirements for each application.
Can I use a t-test to measure the difference among several groups?: A t-test should not be used to measure differences among more than two groups, because the error structure for a t-test will underestimate the actual error when many groups are being compared.

If you want to compare the means of several groups at once, it’s best to use another statistical test such as ANOVA or a post-hoc test.
What is the difference between a one-sample t-test and a paired t-test?: A one-sample t-test is used to compare a single population to a standard value (for example, to determine whether the average lifespan of a specific town is different from the country average).

A paired t-test is used to compare a single population before and after some experimental intervention or at two different points in time (for example, measuring student performance on a test before and after being taught the material).
What does a t-test measure?: A t-test measures the difference in group means divided by the pooled standard error of the two group means.

In this way, it calculates a number (the t-value) illustrating the magnitude of the difference between the two group means being compared, and estimates the likelihood that this difference exists purely by chance (p-value).
Which t-test should I use?: Your choice of t-test depends on whether you are studying one group or two groups, and whether you care about the direction of the difference in group means.

If you are studying one group, use a paired t-test to compare the group mean over time or after an intervention, or use a one-sample t-test to compare the group mean to a standard value. If you are studying two groups, use a two-sample t-test.

If you want to know only whether a difference exists, use a two-tailed test. If you want to know if one group mean is greater or less than the other, use a left-tailed or right-tailed one-tailed test.
What is a t-test?: A t-test is a statistical test that compares the means of two samples. It is used in hypothesis testing, with a null hypothesis that the difference in group means is zero and an alternate hypothesis that the difference in group means is different from zero.
Who uses MLA style?: MLA Style is the second most used citation style (after APA). It is mainly used by students and researchers in humanities fields such as literature, languages, and philosophy.
How do I cite a source with no author, title, or date in MLA?: If information about your source is not available, you can either leave it out of the MLA citation or replace it with something else, depending on the type of information.

No author: Start with the source title.

No title: Provide a description of the source.

No date: Provide an access date for online sources; omit for other sources.
What information do I need to include in an MLA Works Cited entry?: A standard MLA Works Cited entry is structured as follows:

Author. “Title of the Source.” Title of the Container, Other contributors, Version, Number, Publisher, Publication date, Location.

Only include information that is available for and relevant to your source.
What is mixed-methods research?: In mixed-methods research, you use both qualitative and quantitative data collection and analysis methods to answer your research question.
How do I decide which research methods to use?: The research methods you use depend on the type of data you need to answer your research question.

If you want to measure something or test a hypothesis, use quantitative methods. If you want to explore ideas, thoughts and meanings, use qualitative methods.

If you want to analyze a large amount of readily-available data, use secondary data. If you want data specific to your purposes with control over how it is generated, collect primary data.

If you want to establish cause-and-effect relationships between variables, use experimental methods. If you want to understand the characteristics of a research subject, use descriptive methods.
What is statistical significance?: Statistical significance is a term used by researchers to state that it is unlikely their observations could have occurred under the null hypothesis of a statistical test. Significance is usually denoted by a p-value, or probability value.

Statistical significance is arbitrary – it depends on the threshold, or alpha value, chosen by the researcher. The most common threshold is p < 0.05, which means that the data is likely to occur less than 5% of the time under the null hypothesis.

When the p-value falls below the chosen alpha value, then we say the result of the test is statistically significant.
What is a test statistic?: A test statistic is a number calculated by a statistical test. It describes how far your observed data is from the null hypothesis of no relationship between variables or no difference among sample groups.

The test statistic tells you how different two or more groups are from the overall population mean, or how different a linear slope is from the slope predicted by a null hypothesis. Different test statistics are used in different statistical tests.
What are the main assumptions of statistical tests?: Statistical tests commonly assume that:

the data are normally distributed

the groups that are being compared have similar variance

the data are independent

If your data does not meet these assumptions you might still be able to use a nonparametric statistical test, which have fewer requirements but also make weaker inferences.
Can you cite sources in an abstract?: Avoid citing sources in your abstract. There are two reasons for this:

The abstract should focus on your original research, not on the work of others.

The abstract should be self-contained and fully understandable without reference to other sources.

There are some circumstances where you might need to mention other sources in an abstract: for example, if your research responds directly to another study or focuses on the work of a single theorist. In general, though, don’t include citations unless absolutely necessary.
What is the purpose of an abstract?: An abstract is a concise summary of an academic text (such as a journal article or dissertation). It serves two main purposes:

To help potential readers determine the relevance of your paper for their own research.

To communicate your key findings to those who don’t have time to read the whole paper.

Abstracts are often indexed along with keywords on academic databases, so they make your work more easily findable. Since the abstract is the first thing any reader sees, it’s important that it clearly and accurately summarizes the contents of your paper.
Where does the abstract go in an APA paper?: In an APA Style paper, the abstract is placed on a separate page after the title page (page 2).
How long should an APA abstract be?: An APA abstract is around 150–250 words long. However, always check your target journal’s guidelines and don’t exceed the specified word count.
Are titles capitalized in MLA?: Yes. MLA style uses title case, which means that all principal words (nouns, pronouns, verbs, adjectives, adverbs, and some conjunctions) are capitalized.

This applies to titles of sources as well as the title of, and subheadings in, your paper. Use MLA capitalization style even when the original source title uses different capitalization.
Are article titles italicized in MLA?: The title of an article is not italicized in MLA style, but placed in quotation marks. This applies to articles from journals, newspapers, websites, or any other publication. Use italics for the title of the source where the article was published. For example:

“A Complete Guide to MLA Citation” is published on the Scribbr website.

Use the same formatting in the Works Cited entry and when referring to the article in the text itself.
How do you write a book title in MLA?: In MLA style, book titles appear in italics, with all major words capitalized. If there is a subtitle, separate it from the main title with a colon and a space (even if no colon appears in the source). For example:

Dreams from My Father: A Story of Race and Inheritance

The format is the same in the Works Cited list and in the text itself. However, when you mention the book title in the text, you don’t have to include the subtitle.

The title of a part of a book—such as a chapter, or a short story or poem in a collection—is not italicized, but instead placed in quotation marks.
How do I find the DOI of an article?: The DOI is usually clearly visible when you open a journal article on an academic database. It is often listed near the publication date, and includes “doi.org” or “DOI:”. If the database has a “cite this article” button, this should also produce a citation with the DOI included.

If you can’t find the DOI, you can search on Crossref using information like the author, the article title, and the journal name.
How do I format a DOI in MLA style?: In MLA style citations, format a DOI as a link, including “https://doi.org/” at the start and then the unique numerical code of the article.

https://doi.org/10.1177/1464700107078139

DOIs are used mainly when citing journal articles in MLA.
Why are DOIs important?: A DOI is a unique identifier for a digital document. DOIs are important in academic citation because they are more permanent than URLs, ensuring that your reader can reliably locate the source.

Journal articles and ebooks can often be found on multiple different websites and databases. The URL of the page where an article is hosted can be changed or removed over time, but a DOI is linked to the specific document and never changes.
What is a confounding variable?: A confounding variable, also called a confounder or confounding factor, is a third variable in a study examining a potential cause-and-effect relationship.

A confounding variable is related to both the supposed cause and the supposed effect of the study. It can be difficult to separate the true effect of the independent variable from the effect of the confounding variable.

In your research design, it’s important to identify potential confounding variables and plan how you will reduce their impact.
What is the difference between discrete and continuous variables?: Discrete and continuous variables are two types of quantitative variables:

Discrete variables represent counts (e.g. the number of objects in a collection).

Continuous variables represent measurable amounts (e.g. water volume or weight).
What is the difference between quantitative and categorical variables?: Quantitative variables are any variables where the data represent amounts (e.g. height, weight, or age).

Categorical variables are any variables where the data represent groups. This includes rankings (e.g. finishing places in a race), classifications (e.g. brands of cereal), and binary outcomes (e.g. coin flips).

You need to know what type of variables you are working with to choose the right statistical test for your data and interpret your results.
What are independent and dependent variables?: You can think of independent and dependent variables in terms of cause and effect: an independent variable is the variable you think is the cause, while a dependent variable is the effect.

In an experiment, you manipulate the independent variable and measure the outcome in the dependent variable. For example, in an experiment about the effect of nutrients on crop growth:

The independent variable is the amount of nutrients added to the crop field.

The dependent variable is the biomass of the crops at harvest time.

Defining your variables, and deciding how you will manipulate and measure them, is an important part of experimental design.
What is the most recent edition of the MLA Handbook?: The MLA Handbook is currently in its 9th edition, published in 2021.

This quick guide to MLA style explains the latest guidelines for citing sources and formatting papers according to MLA.
What is the easiest way to create MLA citations?: The fastest and most accurate way to create MLA citations is by using Scribbr’s MLA Citation Generator.

Search by book title, page URL or journal DOI to automatically generate flawless citations, or cite manually using the simple citation forms.
What font and size is used in MLA format?: MLA recommends using 12-point Times New Roman, since it’s easy to read and installed on every computer. Other standard fonts such as Arial or Georgia are also acceptable. If in doubt, check with your supervisor which font you should be using.
What is experimental design?: Experimental design means planning a set of procedures to investigate a relationship between variables. To design a controlled experiment, you need:

A testable hypothesis

At least one independent variable that can be precisely manipulated

At least one dependent variable that can be precisely measured

When designing the experiment, you decide:

How you will manipulate the variable(s)

How you will control for any potential confounding variables

How many subjects or samples will be included in the study

How subjects will be assigned to treatment levels

Experimental design is essential to the internal and external validity of your experiment.
What is the difference between internal and external validity?: Internal validity is the degree of confidence that the causal relationship you are testing is not influenced by other factors or variables.

External validity is the extent to which your results can be generalized to other contexts.

The validity of your experiment depends on your experimental design.
What types of source are cited as a personal communication in APA Style?: In APA Style, all sources that are not retrievable for the reader are cited as personal communications. In other words, if your source is private or inaccessible to the audience of your paper, it’s a personal communication.

Common examples include conversations, emails, messages, letters, and unrecorded interviews or performances.
Should interviews be included in an APA reference list?: Interviews you conducted yourself are not included in your reference list, but instead cited in the text as personal communications.

Published or recorded interviews are included in the reference list. Cite them in the usual format of the source type (for example, a newspaper article, website or YouTube video).
How do I cite social media content in APA Style?: To cite a public post from social media, use the first 20 words of the post as a title, include the date it was posted and a URL, and mention the author’s username if they have one:

Dorsey, J. [@jack]. (2018, March 1). We’re committing Twitter to help increase the collective health, openness, and civility of public conversation, and to hold ourselves publicly [Tweet]. Twitter. https://twitter.com/jack/status/969234275420655616

To cite content from social media that is not publicly accessible (e.g. direct messages, posts from private groups or user profiles), cite it as a personal communication in the text, but do not include it in the reference list:

When contacted online, the minister stated that the project was proceeding “according to plan” (R. James, Twitter direct message, March 25, 2017).
How do I cite a source with no page numbers in APA Style?: When you quote or paraphrase a specific passage from a source, you need to indicate the location of the passage in your in-text citation. If there are no page numbers (e.g. when citing a website) but the text is long, you can instead use section headings, paragraph numbers, or a combination of the two:

(Caulfield, 2019, Linking section, para. 1).

Section headings can be shortened if necessary. Kindle location numbers should not be used in ebook citations, as they are unreliable.

If you are referring to the source as a whole, it’s not necessary to include a page number or other marker.
How do I cite a source with no author in APA Style?: When no individual author name is listed, but the source can clearly be attributed to a specific organization—e.g. a press release by a charity, a report by an agency, or a page from a company’s website—use the organization’s name as the author in the reference entry and in-text citations.

When no author at all can be determined—e.g. a collaboratively edited wiki or an online article published anonymously—use the title in place of the author. In the in-text citation, put the title in quotation marks if it appears in plain text in the reference list, and in italics if it appears in italics in the reference list. Shorten it if necessary.
When should I include an access date in an APA citation?: APA Style usually does not require an access date. You never need to include one when citing journal articles, e-books, or other stable online sources.

However, if you are citing a website or online article that’s designed to change over time, it’s a good idea to include an access date. In this case, write it in the following format at the end of the reference: Retrieved October 19, 2020, from https://www.uva.nl/en/about-the-uva/about-the-university/about-the-university.html
What is the most current edition of the APA manual?: The 7th edition APA Manual, published in October 2019, is the most current edition. However, the 6th edition, published in 2009, is still used by many universities and journals.
Where can I buy or download the APA Manual 7th edition?: The APA Manual 7th edition can be purchased at Amazon as a hardcover, paperback or spiral-bound version. You can also buy an ebook version at RedShelf.
When will people start using the 7th edition APA Manual?: The American Psychological Association anticipates that most people will start using the 7th edition in the spring of 2020 or thereafter.

It’s best to ask your supervisor or check the website of the journal you want to publish in to see which APA guidelines you should follow.
When should I include the edition in an APA book citation?: If you’re citing from an edition other than the first (e.g. a 2nd edition or revised edition), the edition appears in the reference, abbreviated in parentheses after the book’s title (e.g. 2nd ed. or Rev. ed.).
Do I need to include the publisher’s location in an APA book citation?: In the 7th edition of the APA manual, no location information is required for publishers. The 6th edition previously required you to include the city and state where the publisher was located, but this is no longer the case.
When should I cite a chapter instead of the whole book?: When a book’s chapters are written by different authors, you should cite the specific chapter you are referring to.

When all the chapters are written by the same author (or group of authors), you should usually cite the entire book, but some styles include exceptions to this.

In APA Style, single-author books should always be cited as a whole, even if you only quote or paraphrase from one chapter.

In MLA Style, if a single-author book is a collection of stand-alone works (e.g. short stories), you should cite the individual work.

In Chicago Style, you may choose to cite a single chapter of a single-author book if you feel it is more appropriate than citing the whole book.
Should I include the exact publication date or just the year in an APA journal citation?: In an APA reference list, journal article citations include only the year of publication, not the exact date, month, or season.

The inclusion of volume and issue numbers makes a more specific date unnecessary.
When should I include a DOI or URL in an APA journal citation?: In an APA journal citation, if a DOI (digital object identifier) is available for an article, always include it.

If an article has no DOI, and you accessed it through a database or in print, just omit the DOI.

If an article has no DOI, and you accessed it through a website other than a database (for example, the journal’s own website), include a URL linking to the article.
How many authors do I include in an APA reference list entry?: You may include up to 20 authors in a reference list entry.

When an article has more than 20 authors, replace the names prior to the final listed author with an ellipsis, but do not omit the final author:

Davis, Y., Smith, J., Caulfield, F., Pullman, H., Carlisle, J., Donahue, S. D., James, F., O’Donnell, K., Singh, J., Johnson, L., Streefkerk, R., McCombes, S., Corrieri, L., Valck, X., Baldwin, F. M., Lorde, J., Wardell, K., Lao, W., Yang, P., . . . O’Brien, T. (2012).
How do I format a DOI in APA Style?: Include the DOI at the very end of the APA reference entry. If you’re using the 6th edition APA guidelines, the DOI is preceded by the label “doi:”. In the 7th edition, the DOI is preceded by ‘https://doi.org/’.

6th edition: doi:10.1177/0894439316660340

7th edition: https://doi.org/10.1177/0894439316660340

APA citation example (7th edition)

Hawi, N. S., & Samaha, M. (2016). The relations among social media addiction, self-esteem, and life satisfaction in university students. Social Science Computer Review, 35(5), 576–586. https://doi.org/10.1177/0894439316660340
What’s the difference between reliability and validity?: Reliability and validity are both about how well a method measures something:

Reliability refers to the consistency of a measure (whether the results can be reproduced under the same conditions).

Validity refers to the accuracy of a measure (whether the results really do represent what they are supposed to measure).

If you are doing experimental research, you also have to consider the internal and external validity of your experiment.
What is sampling?: A sample is a subset of individuals from a larger population. Sampling means selecting the group that you will actually collect data from in your research. For example, if you are researching the opinions of students in your university, you could survey a sample of 100 students.

In statistics, sampling allows you to test a hypothesis about the characteristics of a population.
What’s the difference between quantitative and qualitative methods?: Quantitative research deals with numbers and statistics, while qualitative research deals with words and meanings.

Quantitative methods allow you to test a hypothesis by systematically collecting and analyzing data, while qualitative methods allow you to explore ideas and experiences in depth.
Where does the methodology section go in a research paper?: In a scientific paper, the methodology always comes after the introduction and before the results, discussion and conclusion. The same basic structure also applies to a thesis, dissertation, or research proposal.

Depending on the length and type of document, you might also include a literature review or theoretical framework before the methodology.
What’s the difference between method and methodology?: Methodology refers to the overarching strategy and rationale of your research project. It involves studying the methods used in your field and the theories or principles behind them, in order to develop an approach that matches your objectives.

Methods are the specific tools and procedures you use to collect and analyze data (for example, experiments, surveys, and statistical tests).

In shorter scientific papers, where the aim is to report the findings of a specific study, you might simply describe what you did in a methods section.

In a longer or more complex research project, such as a thesis or dissertation, you will probably include a methodology section, where you explain your approach to answering the research questions and cite relevant sources to support your choice of methods.
Can I submit the same personal statement with every application?: If you’re applying to multiple graduate school programs, you should tailor your personal statement to each application.

Some applications provide a prompt or question. In this case, you might have to write a new personal statement from scratch: the most important task is to respond to what you have been asked.

If there’s no prompt or guidelines, you can re-use the same idea for your personal statement – but change the details wherever relevant, making sure to emphasize why you’re applying to this specific program.

If the application also includes other essays, such as a statement of purpose, you might have to revise your personal statement to avoid repeating the same information.
How long is a personal statement?: The typical length of a personal statement for graduate school applications is between 500 and 1,000 words.

Different programs have different requirements, so always check if there’s a minimum or maximum length and stick to the guidelines. If there is no recommended word count, aim for no more than 1-2 pages.
What’s the difference between a personal statement and a statement of purpose?: A statement of purpose is usually more formal, focusing on your academic or professional goals. It shouldn’t include anything that isn’t directly relevant to the application.

A personal statement can often be more creative. It might tell a story that isn’t directly related to the application, but that shows something about your personality, values, and motivations.

However, both types of document have the same overall goal: to demonstrate your potential as a graduate student and show why you’re a great match for the program.
What font should I use in a Chicago style paper?: Chicago format doesn’t require you to use any specific font, as long as you choose something readable. A good standard choice is 12 pt Times New Roman.
What is the difference between a Chicago reference list and a bibliography?: A reference list is used with Chicago author-date citations.

A bibliography is used with Chicago footnote citations.

Both present the exact same information; the only difference is the placement of the year in source citations:

In a reference list entry, the publication year appears directly after the author’s name.

In a bibliography entry, the year appears near the end of the entry (the exact placement depends on the source type).

There are also other types of bibliography that work as stand-alone texts, such as an annotated bibliography.
What is Turabian style?: Turabian style is a version of Chicago style designed specifically for students and researchers. It follows most Chicago conventions, but also adds extra guidelines for formatting research papers, theses and dissertations.

More information can be found in A Manual for Writers of Research Papers, Theses, and Dissertations by Kate L. Turabian, now in its ninth edition.
What is the difference between footnotes and endnotes?: Footnotes appear at the bottom of the relevant page. Endnotes appear in a list at the end of the text, just before the bibliography.

Chicago note citations follow the exact same format whether they appear in footnotes or endnotes.
Do I have to include a bibliography or reference list?: In Chicago author-date style, your text must include a reference list. It appears at the end of your paper and gives full details of every source you cited.

In notes and bibliography style, you use Chicago style footnotes to cite sources; a bibliography is optional but recommended. If you don’t include one, be sure to use a full note for the first citation of each source.
Should I use short notes or full notes for my Chicago citations?: In Chicago notes and bibliography style, the usual standard is to use a full note for the first citation of each source, and short notes for any subsequent citations of the same source.

However, your institution’s guidelines may differ from the standard rule. In some fields, you’re required to use a full note every time, whereas in some other fields you can use short notes every time, as long as all sources are listed in your bibliography. If you’re not sure, check with your instructor.
When should I use “et al.” in Chicago style citations?: When a source has four or more authors, your in-text citation or footnote should give only the first author’s name followed by “et al.” (Latin for “and others”). This makes your citations more concise.

In your bibliography or reference list, when a source has more than 10 authors, list the first seven followed by “et al.” Otherwise, list every author.
When should I include page numbers in Chicago style citations?: Page numbers should be included in your Chicago in-text citations when:

You’re quoting from the text.

You’re paraphrasing a particular passage.

You’re referring to information from a specific section.

When you’re referring to the overall argument or general content of a source, it’s unnecessary to include page numbers.
How can I create an MLA block quote in Microsoft Word?: To create a correctly formatted block quote in Microsoft Word, follow these steps:

Hit Enter at the beginning and end of the quote.

Highlight the quote and select the Layout menu.

On the Indent tab, change the left indent to 0.5″.

Do not put quotation marks around the quote, and make sure to include an MLA in-text citation after the period at the end.
How are block quotes formatted in MLA?: To format a block quote in MLA:

Introduce the quote with a colon and set it on a new line.

Indent the whole quote 0.5 inches from the left margin.

Place the MLA in-text citation after the period at the end of the block quote.

Then continue your text on a new line (not indented).
How long is a block quote in MLA?: In MLA style, if you quote more than four lines from a source, use MLA block quote formatting.

If you are quoting poetry, use block quote formatting for any quote longer than three lines.
How do I cite a poem in the text in MLA?: An MLA in-text citation should always include the author’s last name, either in the introductory text or in parentheses after a quote.

If line numbers or page numbers are included in the original source, add these to the citation.

If you are discussing multiple poems by the same author, make sure to also mention the title of the poem (shortened if necessary). The title goes in quotation marks.
How do I cite a poem in an MLA Works Cited list?: In the list of Works Cited, start with the poet’s name and the poem’s title in quotation marks. The rest of the citation depends on where the poem was published.

If you read the poem in a book or anthology, follow the format of an MLA book chapter citation. If you accessed the poem online, follow the format of an MLA website citation.
Should I include line numbers in an MLA poetry citation?: Only use line numbers in an MLA in-text citation if the lines are numbered in the original source. If so, write “lines” in the first citation of the poem, and only the numbers in subsequent citations.

If there are no line numbers in the source, you can use page numbers instead. If the poem appears on only one page of a book (or on a website), don’t include a number in the citation.
How do I format a poetry quotation in MLA?: To quote poetry in MLA style, introduce the quote and use quotation marks as you would for any other source quotation.

If the quote includes line breaks, mark these using a forward slash with a space on either side. Use two slashes to indicate a stanza break.

If the quote is longer than three lines, set them off from the main text as an MLA block quote. Reproduce the line breaks, punctuation, and formatting of the original.
What does an APA in-text citation for a website look like?: When citing a web page or online article in APA Style, the in-text citation consists of the author’s last name and year of publication. For example: (Worland & Williams, 2015). Note that the author can also be an organization. For example: (American Psychological Association, 2019).

If you’re quoting you should also include a locator. Since web pages don’t have page numbers, you can use one of the following options:

Paragraph number: (Smith, 2018, para. 15).

Heading or section name: (CDC, 2020, Flu Season section)

Abbreviated heading: (CDC, 2020, “Key Facts” section)
When should I include a page number in an APA in-text citation?: Always include page numbers in the APA in-text citation when quoting a source. Don’t include page numbers when referring to a work as a whole – for example, an entire book or journal article.

If your source does not have page numbers, you can use an alternative locator such as a timestamp, chapter heading or paragraph number.
How do I cite a source with an unknown author or publication date in APA?: No author

Instead of the author’s name, include the first few words of the work’s title in the in-text citation. Enclose the title in double quotation marks when citing an article, web page or book chapter. Italicize the title of periodicals, books, and reports.

No publication date

If the publication date is unknown, use “n.d.” (no date) instead. For example: (Johnson, n.d.).
When should I use “et al.” in APA in-text citations?: The abbreviation “et al.” (meaning “and others”) is used to shorten in-text citations with three or more authors. Here’s how it works:

Only include the first author’s last name, followed by “et al.”, a comma and the year of publication, for example (Taylor et al., 2018).
How can I get better at proofreading?: Whether you’re publishing a blog, submitting a research paper, or even just writing an important email, there are a few techniques you can use to make sure it’s error-free:

Take a break: Set your work aside for at least a few hours so that you can look at it with fresh eyes.

Proofread a printout: Staring at a screen for too long can cause fatigue – sit down with a pen and paper to check the final version.

Use digital shortcuts: Take note of any recurring mistakes (for example, misspelling a particular word, switching between US and UK English, or inconsistently capitalizing a term), and use Find and Replace to fix it throughout the document.

If you want to be confident that an important text is error-free, it might be worth choosing a professional proofreading service instead.
What is the difference between proofreading and editing?: Editing and proofreading are different steps in the process of revising a text.

Editing comes first, and can involve major changes to content, structure and language. The first stages of editing are often done by authors themselves, while a professional editor makes the final improvements to grammar and style (for example, by improving sentence structure and word choice).

Proofreading is the final stage of checking a text before it is published or shared. It focuses on correcting minor errors and inconsistencies (for example, in punctuation and capitalization). Proofreaders often also check for formatting issues, especially in print publishing.
How much does professional proofreading cost?: The cost of proofreading depends on the type and length of text, the turnaround time, and the level of services required. Most proofreading companies charge per word or page, while freelancers sometimes charge an hourly rate.

For proofreading alone, which involves only basic corrections of typos and formatting mistakes, you might pay as little as $0.01 per word, but in many cases, your text will also require some level of editing, which costs slightly more.

It’s often possible to purchase combined proofreading and editing services and calculate the price in advance based on your requirements.
What qualifications do you need to become a proofreader?: There are many different routes to becoming a professional proofreader or editor. The necessary qualifications depend on the field – to be an academic or scientific proofreader, for example, you will need at least a university degree in a relevant subject.

For most proofreading jobs, experience and demonstrated skills are more important than specific qualifications. Often your skills will be tested as part of the application process.

To learn practical proofreading skills, you can choose to take a course with a professional organization such as the Society for Editors and Proofreaders. Alternatively, you can apply to companies that offer specialized on-the-job training programmes, such as the Scribbr Academy.
Is a newspaper article a primary or secondary source?: Articles in newspapers and magazines can be primary or secondary depending on the focus of your research.

In historical studies, old articles are used as primary sources that give direct evidence about the time period. In social and communication studies, articles are used as primary sources to analyze language and social relations (for example, by conducting content analysis or discourse analysis).

If you are not analyzing the article itself, but only using it for background information or facts about your topic, then the article is a secondary source.
Is a movie a primary or secondary source?: A fictional movie is usually a primary source. A documentary can be either primary or secondary depending on the context.

If you are directly analyzing some aspect of the movie itself – for example, the cinematography, narrative techniques, or social context – the movie is a primary source.

If you use the movie for background information or analysis about your topic – for example, to learn about a historical event or a scientific discovery – the movie is a secondary source.

Whether it’s primary or secondary, always properly cite the movie in the citation style you are using. Learn how to create an MLA movie citation or an APA movie citation.
How can you tell if a source is primary or secondary?: To determine if a source is primary or secondary, ask yourself:

Was the source created by someone directly involved in the events you’re studying (primary), or by another researcher (secondary)?

Does the source provide original information (primary), or does it summarize information from other sources (secondary)?

Are you directly analyzing the source itself (primary), or only using it for background information (secondary)?

Some types of source are nearly always primary: works of art and literature, raw statistical data, official documents and records, and personal communications (e.g. letters, interviews). If you use one of these in your research, it is probably a primary source.

Always make sure to properly cite your sources to avoid plagiarism.
What are some examples of secondary sources?: Common examples of secondary sources include academic books, journal articles, reviews, essays, and textbooks.

Anything that summarizes, evaluates or interprets primary sources can be a secondary source. If a source gives you an overview of background information or presents another researcher’s ideas on your topic, it is probably a secondary source.
What are some examples of primary sources?: Common examples of primary sources include interview transcripts, photographs, novels, paintings, films, historical documents, and official statistics.

Anything you directly analyze or use as first-hand evidence can be a primary source, including qualitative or quantitative data that you collected yourself.
What font and font size is used in APA format?: APA Style papers should be written in a font that is legible and widely accessible. For example:

Times New Roman (12pt.)

Arial (11pt.)

Calibri (11pt.)

Georgia (11pt.)

The same font and font size is used throughout the document, including the running head, page numbers, headings, and the reference page. Text in footnotes and figure images may be smaller and use single line spacing.
How do I set up APA format in Word?: The easiest way to set up APA format in Word is to download Scribbr’s free APA format template for student papers or professional papers.

Alternatively, you can watch Scribbr’s 5-minute step-by-step tutorial or check out our APA format guide with examples.
How do I cite in APA format?: APA citations consist of an in-text citation and reference entry. Each source type has its own format; for example, a webpage citation is different from a book citation.

Use Scribbr’s free APA Citation Generator to generate flawless citations in seconds or take a look at our APA citation examples.
Who uses APA style?: APA format is widely used by professionals, researchers, and students in the social and behavioral sciences, including fields like education, psychology, and business.

Be sure to check the guidelines of your university or the journal you want to be published in to double-check which style you should be using.
Should I include page numbers on every page?: Yes, page numbers are included on all pages, including the title page, table of contents, and reference page. Page numbers should be right-aligned in the page header.

To insert page numbers in Microsoft Word or Google Docs, click ‘Insert’ and then ‘Page number’.
What citation styles does the Scribbr Citation Generator support?: The Scribbr Citation Generator currently supports the following citation styles, and we’re working hard on supporting more styles in the future.

APA (6th edition and 7th edition)

MLA (8th edition)

Scribbr uses industry-standard citation styles from the Citation Styles Language project.
Should I check my paper for plagiarism before submitting it to my instructor?: If you’ve correctly cited all the sources you used, then you do not need to use a plagiarism checker before submitting your paper to your instructor. However, if you want to be sure that you didn’t forget to cite anything, then you can use a plagiarism checker yourself.

There are both free plagiarism checkers and paid plagiarism checkers, such as the Scribbr Plagiarism Checker.

To help you, we compared popular plagiarism checkers to find out which one is best.

Best plagiarism checker comparison
Can you plagiarize your own work?: Although it sounds contradictory, you can indeed plagiarize your own work. This is called self-plagiarism. Self-plagiarism goes against the expectations of the reader that the paper you submitted is new and original.

You can plagiarize yourself by, for instance:

Submitting a document you previously submitted for a different course

Using ideas or data from a previous paper without correctly citing yourself as the source

Although self-plagiarism is often unintentional, it can have serious consequences. Be sure to cite your previous work or discuss the decision to use your old paper with your professor.
Is paraphrasing considered plagiarism?: Paraphrasing without crediting the original author is a form of plagiarism, because you’re presenting someone else’s ideas as if they were your own.

However, paraphrasing is not plagiarism if you correctly cite the source. This means including an in-text citation and a full reference, formatted according to your required citation style.

As well as citing, make sure that any paraphrased text is completely rewritten in your own words.
What is the difference between plagiarism and paraphrasing?: Plagiarism means using someone else’s words or ideas and passing them off as your own. Paraphrasing means putting someone else’s ideas in your own words.

So when does paraphrasing count as plagiarism?

Paraphrasing is plagiarism if you don’t properly credit the original author.

Paraphrasing is plagiarism if your text is too close to the original wording (even if you cite the source). If you directly copy a sentence or phrase, you should quote it instead.

Paraphrasing is not plagiarism if you put the author’s ideas completely in your own words and properly cite the source.
Is it plagiarism if you cite the source?: If you’ve properly paraphrased or quoted and correctly cited the source, you are not committing plagiarism.

However, the word correctly is vital. In order to avoid plagiarism, you must adhere to the guidelines of your citation style (e.g. APA or MLA).

You can use the Scribbr Plagiarism Checker to make sure you haven’t missed any citations, while our Citation Checker ensures you’ve properly formatted your citations in APA style.
Are plagiarism checkers accurate?: The accuracy depends on the plagiarism checker you use. Scribbr is the most accurate plagiarism checker. Many free plagiarism checkers fail to detect all plagiarism or falsely flag text as plagiarism.

Take a look at this comparison of free and paid plagiarism checkers for students to find the most accurate plagiarism checker.

The accuracy is determined by two factors: the algorithm (which recognizes the plagiarism) and the size of the database (with which your document is compared).

Size of the database

Many free plagiarism checkers only check your paper against websites – not against books, journals or papers previously submitted by other students. Therefore, these plagiarism checkers are not very accurate, as they miss a lot of plagiarism.

Algorithm

Most plagiarism checkers are only able to detect “direct plagiarism”, or instances where the sentences are exactly the same as in the original source. However, a good plagiarism checker is also able to detect “patchwork plagiarism” (sentences where some words are changed or synonyms are used).
What happens if you plagiarize?: The consequences of plagiarism vary depending on the type of plagiarism and the context in which it occurs. For example, submitting a whole paper by someone else will have the most severe consequences, while accidental citation errors are considered less serious.

If you’re a student, then you might fail the course, be suspended or expelled, or be obligated to attend a workshop on plagiarism. It depends on whether it’s your first offense or whether you’ve done it before.

As an academic or professional, plagiarizing seriously damages your reputation. You might also lose your research funding and/or your job, and you could even face legal consequences for copyright infringement.

	Full note	Short note	Bibliography
2 authors	Anna Burns and Robert Smith	Burns and Smith	Burns, Anna, and Robert Smith.
3 authors	Anna Burns, Robert Smith, and Judith Green	Burns, Smith, and Green	Burns, Anna, Robert Smith, and Judith Green.
4+ authors	Anna Burns et al.	Burns et al.	Burns, Anna, Robert Smith, Judith Green, and Maggie White.

Type	Example
Full note	1. “An Introduction to Research Methods,” Scribbr, accessed June 11, 2020, https://www.scribbr.com/category/methodology/.
Short note	2. Scribbr, “Research Methods.”
Bibliography	Scribbr. “An Introduction to Research Methods.” Accessed June 11, 2020. https://www.scribbr.com/category/methodology/.

Number of authors	In-text citation	Works Cited entry
1 author	(Moore 37)	Moore, Jason W.
2 authors	(Moore and Patel 37)	Moore, Jason W., and Raj Patel.
3+ authors	(Moore et al. 37)	Moore, Jason W., et al.

Longitudinal study	Cross-sectional study
Repeated observations	Observations at a single point in time
Observes the same group multiple times	Observes different groups (a “cross-section”) in the population
Follows changes in participants over time	Provides snapshot of society at a given point