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.
8 min read · Reviewed 2026 · Written and reviewed by Chris McGarrigle
The research onion is a layered model widely used in business and social science methodology teaching, associated with Saunders, Lewis and Thornhill's Research Methods for Business Students. Consult the current edition for the authoritative account.
Used well, it is a sequence of decisions where each layer constrains the next. Used badly, it is a picture pasted into chapter three with no explanation.
Working from the outside in
Each layer answers a different question about your study.
- Philosophy: what counts as valid knowledge here?
- Approach: are you testing theory or building it?
- Strategy: what overall design will you run?
- Choices: single method, multiple methods, or mixed?
- Time horizon: a snapshot, or change over time?
- Techniques and procedures: how you collect and analyse data.
Coherence is the whole point
The layers must be consistent. An interpretivist philosophy paired with hypothesis testing on a random sample is incoherent, and an examiner will notice immediately. If a later layer will not fit, an earlier layer was wrong.
Write it as prose, not as a diagram
Reproducing the diagram earns nothing. Explaining, in your own words, which layer you selected and what it ruled out is what demonstrates understanding.
Common mistakes
- Pasting the diagram with no discussion.
- Choosing a philosophy label that contradicts the actual analysis.
- Treating the layers as independent choices.
- Citing the onion second-hand without consulting the source text.
Try this: One sentence per layer
- Write one sentence for each of the six layers, naming your choice.
- Add 'which rules out…' to each sentence.
- Check that no two sentences contradict one another.
- Expand each into a paragraph for your methodology chapter.
Do it in SuperDiss
Click through each layer and record your choice and justification.
Open the interactive research onionStudents also ask
- What is the research onion?
- The research onion, from Saunders, Lewis and Thornhill, is a six-layer model of research design: philosophy, approach to theory development, methodological choice, strategy, time horizon, and techniques and procedures. You peel from the outside in.
- Do I have to use the research onion?
- No, but it is the most widely taught scaffold in UK business and social science dissertations, and it makes a methodology chapter easy for a marker to follow.
- What goes in each layer?
- Philosophy (positivism, interpretivism, pragmatism), approach (deductive, inductive, abductive), choice (mono, multi or mixed method), strategy (survey, case study, ethnography, experiment), time horizon (cross-sectional or longitudinal), and finally your data collection and analysis techniques.
Related research: design the methodology
Choose philosophy, approach, sampling and ethics you can defend in the viva.
How to choose a methodology
A decision path from research question to methodology, plus how to write the justification examiners are looking for.
Research philosophy explained: ontology, epistemology and axiology
A clear introduction to research philosophy for dissertations: ontology, epistemology and axiology, and how they shape your methodology choices.
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.
How to get ethical approval
What ethics committees actually look for, the documents you need, and the mistakes that cause applications to be returned.
Continue your dissertation journey
- How to choose a methodology
- Qualitative vs quantitative research
- Research philosophy explained: ontology, epistemology and axiology
- Interpretivism vs positivism: which fits your dissertation?
- Sampling explained
Browse every guide in research methodology.
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.
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.
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.