What is a Post Hoc Analysis?
A post hoc analysis is any analysis of a dataset that was not pre-specified prior to data collection. In pharma, it is most often used in the context of clinical trials and refers to analyses which were not specified in the original statistical analysis plan. Post hoc analyses may look at subgroups of interest or different endpoints than those in the primary analyses.

Post hoc analyses are often conducted following primary result communication and publication of clinical trials, especially pivotal studies. They can be a way of better understanding the trial results and population, although caution should be used given the higher potential for bias and cherry-picking once the broader results are known.