Power analyses and sample size calculations are important parts of many research projects. Often, before data are even collected, it is necessary to calculate and justify the required sample size for ...

In epidemiologic studies and disease prevention trials, interest often involves estimation of the relationship between some disease endpoints and individual exposure. In some studies, due to the ...

Low statistical power undermines the purpose of scientific research; it reduces the chance of detecting a true effect. Perhaps less intuitively, low power also reduces the likelihood that a ...

Journal of the Royal Statistical Society. Series D (The Statistician), Vol. 46, No. 2, Special Issue: Sample Size Determination (1997), pp. 231-237 (7 pages) A simple general formula is given for ...