Definition

Preregistration

Publicly time-stamping your hypotheses, design, and analysis plan before collecting data, so confirmatory and exploratory results stay distinguishable.

Preregistration (on OSF, ClinicalTrials.gov, PROSPERO for reviews) commits you to an analysis before the data can tempt you — the antidote to p-hacking and HARKing (hypothesizing after results are known). Deviations are allowed; they just must be disclosed as such.

Registered reports go further: journals peer-review the protocol and accept the paper in principle before results exist, neutralizing publication bias too. Neither forbids exploration — they label it.