How to Write a Delphi Study Protocol Before You Start

A Delphi study protocol is not a formality — it's the document that makes your study replicable, your methods chapter defensible, and your consensus claims credible. Everything reviewers and examiners will scrutinize most closely — your expert definition, your consensus threshold, your stopping rule — should exist in writing before Round 1 opens. Writing it afterward is the single most reliable way to invite a major revision.

What a Protocol Is (and Isn't)

A Delphi study protocol is a pre-registered record of how the study will be run: who qualifies as a panelist, what rounds will cover, how feedback will be structured, and what counts as consensus. It's not a detailed methods chapter — that comes later, drawing from the protocol. The protocol is the plan; the methods chapter is the record of what happened.

In clinical research, protocols are formally registered before data collection begins. For academic thesis research, a written protocol filed with your supervisor before recruitment starts serves the same function: it prevents anyone from claiming you designed the study to fit the results.

Research Question and Study Purpose

The protocol opens with a clear statement of what the study is designed to do. Not "to explore expert opinion on X" — that's too vague to anchor any design decision. A usable protocol statement specifies what the study output will be: a priority-ranked list, a set of validated standards, a consensus-based definition, a forecast, or a set of clinical recommendations. This statement determines everything that follows.

Expert Definition and Inclusion Criteria

Write your expert definition before recruiting. It should specify:

A vague definition like "experts in the field" is not a definition — it's a gap that reviewers will flag immediately.

Panel Size and Recruitment Strategy

Specify your target panel size and your rationale. State whether you'll use purposive, snowball, or criterion-based sampling, and why the chosen approach fits your expert population. Include your attrition buffer — how many more panelists you'll recruit than your minimum target.

Questionnaire Development

Describe how Round 1 items will be generated — from literature review, prior qualitative research, expert interviews, or a combination. State whether Round 1 will be open-ended (generating items) or structured (rating predefined items). Describe how items will be piloted before distribution.

Round Procedure

For each round, specify:

Consensus Threshold and Stopping Rule

This is the most critical section of the protocol. State:

All three must be defined here. Defining any of them after seeing data is considered post-hoc and will not survive peer review or a viva examination.

Ethics and Data Protection

State whether ethics approval is required for your study, which body would grant it, and how you will handle: informed consent, anonymity of panelist responses, data storage and retention, and GDPR compliance if any panelist is based in the EU. If your institution's ethics board determines approval is not required for expert surveys, note that determination explicitly.

Timeline

Include a realistic round-by-round timeline covering: recruitment period, each round's open period, analysis and feedback preparation periods, and the target date for final consensus determination. A timeline that doesn't account for recruitment time and between-round analysis is the most common cause of thesis timeline failure.

Where to File It

For thesis research: file it with your supervisor before recruiting. For journal research: consider pre-registering on OSF (Open Science Framework) or equivalent. For clinical research: register on a clinical trials registry before data collection. The act of filing it before recruitment is what distinguishes a prospective protocol from a retrospective description.