Why a time-honoured statistical tool is becoming problematic.

Find out how scientists, from physicists to geneticists, measure their confidence in their results.

What do physicists at CERN mean when they talk about "sigma levels"?

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?