On: Most commonly used statistical tests and implement...

[capnrefsmmat]

No, the base rate. If you're doing a significance test to detect a rare disease that only occurs in a tiny fraction of people, for example, the majority of statistically significant results you obtain will be false, despite having p < 0.05.

This is a common problem in many fields, and you can use false discovery rate control methods to account for it: http://www.statisticsdonewrong.com/p-value.html