Understanding type I and type II errors, statistical power and sample size

Abstract

The results of a clinical trial may be subject to random error because of the variability in the measured data, which arises purely by chance. There are two types of random error - type I error and type II error. In this study, type I and type II errors are explained, and the important concepts of statistical power and sample size estimation are discussed.

Conclusion: The most important way of minimising random errors is to ensure adequate sample size; that is, a sufficient large number of patients should be recruited for the study.

Keywords: Power; Sample size; Type I error; Type II error.