What is the purpose of post hoc analysis?

Post hoc analysis serves a specific function in the research process, particularly in the context of clinical trials. Its primary purpose is to re-examine data after a trial has been completed to uncover additional insights that were not originally specified in the trial's design. This approach can help researchers identify patterns, trends, or effects that emerged only after the data was collected and analyzed for the primary outcomes. For instance, researchers may use post hoc analysis to explore subgroups or to examine secondary outcomes that were not the primary focus of the original hypothesis.

This method is crucial for understanding the data more thoroughly and can contribute to generating new hypotheses for future studies. It is important to note that while post hoc analyses can provide valuable insights, they should be interpreted with caution, as they can increase the risk of Type I errors due to multiple comparisons being made without pre-specified hypotheses.

The other options, while related to various aspects of clinical trials, do not accurately reflect the purpose of post hoc analysis. Evaluating patient demographics focuses on baseline characteristics, assessing compliance with trial protocols pertains to adherence to the study design, and developing new trial designs involves planning future research rather than analyzing completed studies.