Jun
28
p values, the cliff effect and the nature of evidence
I've been thinking about p values quite a bit recently - prompted by a other bloggers and by some journal work. One interesting phenomenon in this area is the cliff effect: a supposed abrupt shift in researchers' confidence in an effect when moving from p > .05 to p < .05 (assuming that alpha is set at .05, as it usually is).
The p value cliff effect is interesting for a number of reasons (e.g., as a possible cause of dichotomous thinking about effects - see Rosenthal & Gaito, 1963). Personally (e.g., Baguley, 2012a), I think that the tendency to dichotomous thinking is more subtle and complex - and not just a consequence of the cliff effect. Furthermore, there is some doubt about the prevalence of the cliff effect.
The p value cliff effect is interesting for a number of reasons (e.g., as a possible cause of dichotomous thinking about effects - see Rosenthal & Gaito, 1963). Personally (e.g., Baguley, 2012a), I think that the tendency to dichotomous thinking is more subtle and complex - and not just a consequence of the cliff effect. Furthermore, there is some doubt about the prevalence of the cliff effect.
