The following list clarifies some issues that are commonly misunderstood regarding p-values:[2][3][4] Issues 1 and 2 can be illustrated by analogy to the Prosecutor's Fallacy in their shared underlying 2×2 contingency table format, where the user's convenient 90° rotation of attention replaces the intended sample space with an illicit sample space.
Several statistical techniques have been developed to prevent this from happening, allowing significance levels for single and multiple comparisons to be directly compared.
These techniques generally require a higher significance threshold for individual comparisons, so as to compensate for the number of inferences being made.
[citation needed] The webcomic xkcd satirized misunderstandings of p-values by portraying scientists investigating the claim that eating jellybeans caused acne.
In general, the family-wise error rate (FWER)—the probability of obtaining at least one false positive—increases with the number of tests performed.