In statistics, per-comparison error rate (PCER) is the probability of a

Type I error In statistical hypothesis testing, a type I error is the mistaken rejection of an actually true null hypothesis (also known as a "false positive" finding or conclusion; example: "an innocent person is convicted"), while a type II error is the f ...

in the absence of any multiple hypothesis testing correction. This is a liberal error rate relative to the

false discovery rate In statistics, the false discovery rate (FDR) is a method of conceptualizing the rate of type I errors in null hypothesis testing when conducting multiple comparisons. FDR-controlling procedures are designed to control the FDR, which is the expe ...

and

family-wise error rate In statistics, family-wise error rate (FWER) is the probability of making one or more false discoveries, or type I errors when performing multiple hypotheses tests. Familywise and Experimentwise Error Rates Tukey (1953) developed the concept of ...

, in that it is always less than or equal to those rates.

References

Statistical hypothesis testing Rates {{statistics-stub