A common misperception is that *p* = .05 means there is a 5% probability of obtaining the observed result by chance. The correct interpretation is that there is a 5% probability of getting a result this large (or larger) *if* the effect size equals zero.

## What is a *p *value?

A *p* value is the answer to the question: if the null hypothesis were true, how likely is this result? A low *p* says “highly unlikely”, making the null improbable and therefore rejectable.

In substantive terms, a *p* value really tells us very little. As the *p *value is a confounded index, it is never a good idea to interpret results on the basis of *p* values.