protocol
Meaning of protocol: Fixing the plan in writing before anything starts is what stops a result being explained away by choices made after the fact.
Definition of protocol
A protocol is the written plan setting out exactly how a treatment, procedure or research study will be carried out: which steps are taken, in what order, by whom, and to what standard. Committing it to paper before the work begins is what makes the process repeatable and lets a later reader judge whether it was actually followed.
What goes into a research protocol?
A protocol for a research study is a long document, and every section exists to remove a choice that could otherwise be made after the results are known. It states the question and the primary outcome measure. It defines who may take part and who may not. It specifies the intervention, the comparison it is measured against, and how participants are assigned between them. It fixes the schedule of visits, tests and samples. It sets out the sample size and the reasoning behind it, the statistical analysis to be used, the safety monitoring arrangements, and the conditions under which the study would stop early. Changes after the start are possible but must be written as formal amendments, dated and approved, so that the record shows what was planned and what was altered.
How is a treatment protocol different?
| Type | Purpose | Who it binds |
|---|---|---|
| Research protocol | Answer a question reliably enough to publish | Investigators, monitors, ethics committees |
| Treatment protocol | Deliver an established regimen the same way every time | The clinical team caring for the patient |
| Standard operating procedure | Keep a routine task consistent between staff and sites | Anyone performing that task |
A chemotherapy protocol naming drugs, doses, order and interval is the second kind. It standardizes care rather than testing a hypothesis, though the wording of the two can look similar on the page.
Why does departing from it matter?
A departure from the written plan is recorded as a protocol deviation, and a serious one as a violation. These are tracked because they affect how the results can be read: an analysis that includes everyone as originally assigned answers a different question from one that includes only those who followed the plan exactly. Registering a protocol publicly before enrollment begins also makes it hard to switch the outcome measure later to whichever result turned out best. The wider framework of expectations for how trials are run is described as good clinical practice.
Used in a sentence
The patient was enrolled in a clinical trial following the study's written protocol.
Good to know
A research protocol and a treatment protocol are both standardized plans, but a research protocol additionally fixes in advance how the results will be measured and analyzed, which is what makes those results interpretable.
Word origin
Where “protocol” comes from
From Greek protokollon, originally the first sheet glued to the front of a manuscript to record its authenticity, later extended to mean a formal agreed document.