This word is used in two (similar but different) ways.
- For empirical studies in general, the experimental protocol is a document that describes the way that a study is to be performed. It should be written before the study begins and evaluated and tested through a 'dry run'. During the actual study, any divergences from the protocol should be recorded.
- In the context of protocol analysis as a qualitative data analysis technique based upon the use of think-aloud, the protocol is a categorisation of possible utterances that is used to analyse the particular sequence produced by a participant while performing a task as well as to strip out irrelevant material.