**50**wrote:

Hello, I am studying correction for multiple testing and have some trouble understanding the FDR.

- significance level=0.05
- number of tests=100

**For Bonferroni correction,** p-value should be multiplied by the number of tests.
So, the raw p-value(0.001) * number of tests(100) = Bonferroni corrected p-value(0.1). So we can say that this p-value is not significant (when alpha=0.05).

Or, we can set the cutoff for Bonferroni correction as 0.05/100 = 0.0005. So the p-value of 0.001 is not significant, as this 0.001 is greater than 0.0005.

**For FDR correction,** p-value is calculated as: p-value * rank/number of tests. If this p-value ranks fifth among 100 tests, raw p-value(0.001) * 5/100 = FDR corrected p-value(0.00005). So we can say that this p-value is still significant.

My question is, then how can I set the cutoff for FDR correction? (as 0.05/100 in Bonferroni correction above)

**5.5k**• written 18 months ago by kelly.wang135 •

**50**