Type II error

Definition

Type II error occurs when we fail to reject a null hypothesis that is actually false. In other words, it's the mistake of accepting the null hypothesis when we should have rejected it.

Related terms

Power: Power is the probability of correctly rejecting a false null hypothesis. It represents our ability to detect an effect or difference when one truly exists.

Type I error: Type I error is the opposite of type II error. It occurs when we reject a null hypothesis that is actually true.

Significance level (alpha): The significance level is the threshold at which we decide whether to reject or fail to reject the null hypothesis. It determines how much evidence we need against the null hypothesis before rejecting it.