Tag Archives: effect size

In defence of the P-value

(graphic by Chen-Pan Liao via wikimedia.org)

The P-value (and by extension, the entire enterprise of hypothesis-testing in statistics) has been under assault lately. John Ioannadis’ famous “Why most published research findings are false” paper didn’t start the fire, but it threw quite a bit of gasoline on it. David Colquhoun’s recent “An investigation of the false discovery rate and the misinterpretation of P-values” raised the stakes by opening with a widely quoted and dramatic (but also dramatically silly) proclamation that “If you use P=0.05 to suggest that you have made a discovery, you will be wrong at least 30% of the time.”* While I could go on citing examples of the pushback against P, it’s inconceivable that you’ve missed all this, and it’s well summarized by a recent commentary in Nature News. Even the webcomic xkcd has piled on. Continue reading