How to calculate sample size and why

Abstract

Why: Calculating the sample size is essential to reduce the cost of a study and to prove the hypothesis effectively. How: Referring to pilot studies and previous research studies, we can choose a proper hypothesis and simplify the studies by using a website or Microsoft Excel sheet that contains formulas for calculating sample size in the beginning stage of the study. More: There are numerous formulas for calculating the sample size for complicated statistics and studies, but most studies can use basic calculating methods for sample size calculation. © 2013 by The Korean Orthopaedic Association.