Interim Analysis and Data Monitoring in Clinical Trials

Abstract

Sample mean of N observations The variance of sample mean =σ2/N. The information about the population mean provided by the sample mean is N/σ2. If σ2=1, the information about the population mean provided by the sample of N observation is simply the sample size N. This is the definition of statistical information which can be also interpreted as the clinical information The planned sample size is the minimum clinical and statistical information required to achieve the desired power for detecting a minimum clinically meaningful difference at a pre-determined risk of typeⅠerror.