Qualitative vs quantitative research

The real difference between qualitative and quantitative dissertation research, and how to choose based on your question rather than your comfort zone.

8 min read · Reviewed 2026

The choice is not about whether you like numbers. It is about what kind of claim your research question demands, and what kind of evidence can support that claim.

Quantitative work measures and compares. Qualitative work interprets meaning. Mixed methods does both, deliberately, and costs roughly twice as much time.

Match the design to the claim

If your question asks how much, how many, or whether a relationship holds across a population, you need measurement, a defensible sample and statistical analysis.

If your question asks how people experience, interpret or justify something, you need depth: interviews, focus groups, documents or observation, analysed for meaning.

What counts as quality differs

Quantitative quality is argued through validity, reliability, sampling and statistical power. Qualitative quality is argued through credibility, transferability, dependability and confirmability — with an audit trail and reflexivity about your own position.

Applying the wrong quality criteria to your design is a reliable way to lose marks. Do not promise generalisability from eight interviews.

Mixed methods, honestly

Mixed methods is legitimate but must be justified by the question, not by indecision. Say explicitly whether the strands run sequentially or concurrently, which one leads, and at what point you integrate the findings.

Common mistakes

  • Choosing a survey because it feels quicker, then having nothing to interpret.
  • Claiming generalisability from a small qualitative sample.
  • Running both strands without explaining how they integrate.
  • Letting the method drive the question instead of the reverse.

Try this: Write both versions

  1. Draft a one-paragraph quantitative design for your question.
  2. Draft a one-paragraph qualitative design for the same question.
  3. For each, note what you could claim and what you could not.
  4. Choose the one whose claims match what your question promises.

Do it in SuperDiss

Work through philosophy, approach and design — and be able to defend each choice.

Open the Methodology Lab

Read next

How to choose a methodology

A decision path from research question to methodology, plus how to write the justification examiners are looking for.

The research onion explained

The research onion as a decision-making tool rather than a diagram to copy: what each layer asks and how the layers constrain each other.

This guide is general educational content. Your institution's regulations, handbook and supervisor's instructions always take precedence. Where a named framework is mentioned, consult the original source text rather than relying on this summary.