Qualitative vs. quantitative research

There are two approaches to conducting empirical research: qualitative research and quantitative research. Each type of research has different objectives and methods, and both are important for gaining different kinds of knowledge.

Quantitative research

Quantitative research is expressed in numbers and graphs. It is used to test or confirm theories and assumptions. This type of research can be used to establish generalizable facts about a topic.

  • Surveys, experimental research, observational research
Qualitative research

Qualitative research is expressed in words. It is used to understand concepts, thoughts or experiences. This type of research enables you to gather in-depth insights on topics that are not well understood.

The differences between quantitative and qualitative research

Quantitative and qualitative research use different methods of data collection and analysis, and they allow you to answer different kinds of research questions.

Qualitative vs. quantitative research
Quantitative researchQualitative Research
Focuses on testing theories and hypothesesFocuses on exploring ideas and formulating a theory or hypothesis
Is analyzed through math and statistical analysisIs analyzed by summarizing, categorizing and interpreting
Mainly expressed in numbers, graphs and tablesMainly expressed in words
Requires many respondentsRequires few respondents
Closed (multiple choice) questionsOpen-ended questions
Key terms are: testing, measurement, objectivity, replicabilityKey terms are: understanding, context, complexity, subjectivity

Data collection methods

Quantitative and qualitative data can be collected using various methods. It is important to use a data collection method that will help answer your research question(s).

Quantitative data collection methods

  • Surveys: List of closed or multiple choice questions that is distributed to a sample (online, in person, or over the phone).
  • Experiments: Situation in which variables are controlled and manipulated to establish cause-and-effect relationships.
  • Observations: Observing people in a natural environment where variables can’t be controlled.

Qualitative data collection methods

  • Interviews: Asking open-ended questions verbally to respondents.
  • Focus groups: Discussion among a group of people about a topic to gather opinions that can be used for further research.
  • Case studies: In-depth study about a person, group, event or organization.
  • Literature review: Survey of published works by other authors.

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When to use qualitative vs. quantitative research

A rule of thumb for deciding whether to use qualitative or quantitative data is:

  • Use quantitative research if you want to confirm or test something (a theory or hypothesis)
  • Use qualitative research if you want to understand something (concepts, thoughts, experiences)

For most research topics you can choose a qualitative, quantitative or mixed methods approach. Which type you choose depends on, among other things, whether you’re taking an inductive vs. deductive research approach; your research question(s); whether you’re doing experimental, correlational, or descriptive research; and practical considerations such as time, money, availability of data and access to respondents.

Research question: How satisfied are students with their studies?

Quantitative research approach

You survey 300 students at your university and ask them questions such as: “on a scale from 1-5, how satisfied are your with your professors?”

You can perform statistical analysis on the data and draw conclusions such as: “on average students rated their professors 4.4”.

Qualitative research approach

You conduct in-depth interviews with 15 students and ask them open-ended questions such as: “How satisfied are you with your studies?”, “What is the most positive aspect of your study program?” and “What can be done to improve the study program?”

Based on the answers you get you can ask follow-up questions to clarify things. You transcribe all interviews using transcription software and try to find commonalities and patterns.

Mixed methods approach

You conduct interviews to find out how satisfied students are with their studies. Through open-ended questions you learn things you never thought about before and gain new insights. Later, you use a survey to test these insights on a larger scale.

It’s also possible to start with a survey to find out the overall trends, followed by interviews to better understand the reasons behind the trends.

How to analyze qualitative and quantitative data

Qualitative or quantitative data by itself can’t prove or demonstrate anything, but has to be analyzed to show its meaning in relation to the research questions. The method of analysis differs for each type of data.

Analyzing quantitative data

Quantitative data is based on numbers. Simple math or more advanced statistical analysis is used to discover commonalities or patterns in the data. The results are often reported in graphs and tables.

Applications such as Excel, SPSS or SAS can be used to calculate things like:

  • Average scores
  • The number of times a particular answer was given
  • The correlation or causation between two or more variables

Analyzing qualitative data

Qualitative data is more difficult to analyze than quantitative data. It consists of text, images or videos instead of numbers.

One of several approaches to analyzing qualitative data is to:

  1. Summarize the data (extract the main points from the answers to your interview questions)
  2. Categorize the data (group similar ideas and themes together, e.g. “professors’ teaching skills” or “personal attention”)
  3. Identify patterns and commonalities
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Raimo Streefkerk

Raimo has a bachelor's and master's degree and has written several papers and theses. He likes to share his knowledge by writing helpful articles.

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