What Is a Pilot Study?

A pilot study is a small preliminary study that tests whether the methods of a planned larger study are workable. It asks "can we do this?" (recruitment, procedures, measurements, adherence) rather than "does it work?".

What a pilot study is for

• Estimating recruitment and retention rates.
• Testing procedures, questionnaires and data collection forms.
• Assessing the acceptability of an intervention.
• Estimating variability to help plan a larger sample (with caution).
• Identifying problems before spending the full budget.

What it is not

A pilot is not simply a small trial. Small studies have wide uncertainty, so an effect "seen" in a pilot should not be reported as proof of effectiveness, and a non-significant pilot does not prove that an intervention does not work.

Planning

1. Define feasibility objectives and progression criteria in advance (for example "proceed if at least 60% of eligible patients agree to join").
2. Choose a sample size justified for feasibility goals, not for hypothesis testing.
3. Report using the CONSORT extension for pilot and feasibility trials, where relevant.
4. Describe how the pilot will inform the main study.

Illustrative example

Invented for teaching. Before a trial of a nurse-led discharge programme, a team runs a 3-month pilot in one ward with 30 patients. They find that 48% of eligible patients consent, follow-up questionnaires are completed by 70%, and 12% of records lack discharge dates. They revise the consent process and data forms before the main trial.

Common pitfalls

• Reporting effectiveness conclusions from a pilot.
• Using pilot data to calculate a sample size without recognising its imprecision.
• Having no progression criteria.

Key takeaways

• Pilot studies test feasibility, not effectiveness.
• Set objectives and progression criteria first.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.