As a general rule an investigator should use parametric tests whenever possible to help minimize the probability of making a Type II error.

Question

Quizplus · Accepted Answer

Parametric tests typically have more power than nonparametric tests, meaning they are better able to detect true differences or relationships between variables. By using a parametric test, an investigator can increase the chance of correctly rejecting a null hypothesis when it is actually false, thus minimizing the risk of a Type II error (failing to detect a true effect). However, there may be situations where nonparametric tests are more appropriate, such as when the data do not meet the assumptions of a parametric test.

As a General Rule an Investigator Should Use Parametric Tests