This type of error refers to the situation where it is concluded that no difference between two groups exists, when in fact it does. The probability of a type II error is often denoted with the symbol β. As the 'power' of a study is defined as the probability of detecting the difference when it does exist, it can be calculated as (1-β). | This type of error refers to the situation where it is concluded that no difference between two groups exists, when in fact it does. The probability of a type II error is often denoted with the symbol β. As the 'power' of a study is defined as the probability of detecting the difference when it does exist, it can be calculated as (1-β). |