A priori

A priori (literally: ‘from the former’) hypotheses are those based on prior research, assumed principles, and deductive reasoning. These hypotheses are developed before a new study begins, guiding the design of experimental studies and evidence synthesis. In statistics, a priori tests are generally considered more credible than a posteriori (post-hoc) tests because they are less subject to bias.

See priors for the definition within a Bayesian context.