When you do quantitative research, you have to consider the reliability and validity of your methods and instruments of measurement.
Reliability tells you how consistently a method measures something. When you apply the same method to the same sample under the same conditions, you should get the same results. If not, the method of measurement may be unreliable.
There are four main types of reliability. Each can be estimated by comparing different sets of results produced by the same method.
|Type of reliability||Measures the consistency of…|
|Test-retest||The same test over time.|
|Interrater||The same test conducted by different people.|
|Parallel forms||Different versions of a test which are designed to be equivalent.|
|Internal consistency||The individual items of a test.|
Continue reading: Types of reliability and how to measure them
Reliability and validity are concepts used to evaluate the quality of research. They indicate how well a method, technique or test measures something. Reliability is about the consistency of a measure, and validity is about the accuracy of a measure.
It’s important to consider reliability and validity when you are creating your research design, planning your methods, and writing up your results, especially in quantitative research.
Reliability vs validity
|What does it tell you?||The extent to which the results can be reproduced when the research is repeated under the same conditions.||The extent to which the results really measure what they are supposed to measure.|
|How is it assessed?||By checking the consistency of results across time, across different observers, and across parts of the test itself.||By checking how well the results correspond to established theories and other measures of the same concept.|
|How do they relate?||A reliable measurement is not always valid: the results might be reproducible, but they’re not necessarily correct.||A valid measurement is generally reliable: if a test produces accurate results, they should be reproducible.|
Continue reading: Reliability vs validity: what’s the difference?
Uncountable nouns, also known as mass nouns or noncount nouns, refer to a mass of something or an abstract concept that can’t be counted (except with a unit of measurement). In contrast, countable nouns can be counted as individual items.
The main rules to remember for uncountable nouns are that they cannot be pluralized, and that they never take indefinite articles (a or an).
Common examples of uncountable nouns
|Type of noun||Examples|
|Abstract concepts and physical phenomena||research, advice, information, knowledge, money, logic, gravity, acceleration, pollution, feedback, traffic, radiation, biomass, lightning|
|Substances, materials and foods||air, water, blood, algae, mud, grass, seaweed, graphite, clay, quartz, rice, flour, meat|
|Elements, chemicals and gases||helium, iron, copper, hydrochloric acid, calcium carbonate, carbon monoxide, methane|
|Disciplines and fields||biology, chemistry, physics, mathematics, geography, psychology, economics, aquaculture, trigonometry|
Continue reading: Recognizing and using uncountable nouns
Apostrophes have two main uses:
- Indicating possession (e.g. The student’s paper)
- Indicating a contraction (e.g. She’s writing a paper)
Contractions should be avoided in academic writing, but possessive apostrophes are used in all types of writing. Make sure to use them correctly, especially when dealing with plurals and abbreviations.
Continue reading: Apostrophes (’)
Commas are used to split up different parts of a sentence, and when used correctly they bring clarity and flow to your writing. They’re probably the most common piece of punctuation in English, which means that they’re often the most misused.
This article takes you through the most important comma rules and the most common mistakes.
Continue reading: Commas (,)
Prepositions are words that show the relationship between elements in a sentence. They can express relationships of place, time, direction, and other abstract or logical connections.
A preposition is usually located directly before the word or phrase that it relates to – the object of the preposition.
- We walked to the shop.
- I’ve been unwell since last Wednesday.
- That gift is for him.
Prepositions are flexible words that are often central to the meaning of a sentence, and it can be tricky to choose the right one. The best way to master them is by reading and practice.
Continue reading: Choosing the right prepositions
The subject of a sentence should always match the verb describing its action. This helps your reader understand who or what is doing something and makes your writing easier to read.
First, identify the subject (the person or thing doing the action) and the verb (the action word) in a sentence. If the subject is singular, the verb describing its action should be singular. If the subject is plural, the verb should be plural.
|Verb||Singular subject + verb||Plural subject + verb|
|Be||The result is significant.||The results are significant.|
|Do||The student does her best.||The students do their best.|
|Become||The child becomes happier.||The children become happier.|
|Cause||That tree causes hay fever.||Those trees cause hay fever.|
|Analyze||The author analyzes the text.||The authors analyze the text.|
While subject-verb agreement is easy in simple sentences like these, it can become tricky in more complex sentences. This article teaches you the most important rules and common mistakes.
Continue reading: Subject-verb agreement