Post hoc analysis
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In a scientific study, post hoc analysis (from Latin post hoc, "after this") consists of analyses that were not specified before seeing the data. This typically creates a multiple testing problem because each potential analysis that is considered is effectively a statistical test. Multiple testing procedures are sometimes used to compensate, but that is often difficult or impossible to do precisely. Post hoc analysis that is conducted and interpreted without adequate consideration of this problem is sometimes called data dredging by critics because the more one looks the more likely something will be found.