Sample Size and Power

This paper sets forth the basic concepts of the calculation of sample size and power in clinical research. It provides the reader with a basic understanding of the relationship between sample size and power and the components within the research, such as the variability of the measure being used as the primary outcome. The paper also discusses a number of general issues related to sample size and power, such as the importance of the difference between clinical and statistical significance, how one approaches trials attempting to establish the equivalence of clinical interventions, and the critical need for appropriate consultation.