Fig. 2.

Demonstration of correction methods for the multiple testing problem. (a) A raw image of the simulated data used in this example. A field of Gaussian random noise was added to a 100 × 100 image with a 50 × 50 square section of signal in the center. (b) Thresholded image of the simulated data using a pixelwise statistical test. The threshold for this test was P < 0.05. Power is high at 0.80, but a number of false positives can be observed. (c) Thresholded image of the simulated data using a Bonferroni FWER correction. The probability of a familywise error was set to 0.05. There are no false positives across the entire set of tests, but power is reduced to 0.16. (d) Thresholded image of the simulated data while controlling the false discovery rate. The FDR for this example was set to 0.05. Out of the results, 4.9% are known to be false positives but power is increased to 0.54.