Why a time-honoured statistical tool is becoming problematic.

In the previous article we looked at a psychological study which claims to provide evidence that certain types of extra-sensory perception exist, using a statistical method called significance testing. But do the results of the study really justify this conclusion?

In March 2011 a highly respected psychology journal published a paper claiming to provide evidence for extra-sensory perception (ESP). The claim was based largely on the results of a very common statistical procedure called significance testing. The experiments provide an excellent way into looking at how significance testing works and at what's problematic about it.