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

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

  1. Write one sentence for each of the six layers, naming your choice.
  2. Add 'which rules out…' to each sentence.
  3. Check that no two sentences contradict one another.
  4. 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 onion

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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.