A tail of two sides: Artificially doubled false positive rates in neuroimaging due to the sidedness choice with t‐tests

One‐sided t ‐tests are widely used in neuroimaging data analysis. While such a test may be applicable when investigating specific regions and prior information about directionality is present, we argue here that it is often mis‐applied, with severe consequences for false positive rate (FPR) control. Conceptually, a pair of one‐sided t ‐tests conducted in tandem (e.g., to test separately for both positive and negative effects), effectively...