Formula For Sample Size Estimation. If the population is N then the corrected sample size should be 186N N185. In brief we outline the basic steps for calculating sample size at the design stage of a clinical study.
Jun 02 2015 If you have a small to moderate population and know all of the key values you should use the standard formula. 2 select the type of study design. Inverse cumulative probability of the standard normal distribution at 1- α 2.
The standard formula for sample size is.
N NX X N 1 where X Z α22 p 1-p MOE 2 and Z α2 is the critical value of the Normal distribution at α2 eg. Sample size to estimate proportion formula is defined as Z 2 x P 1 - P e 2. As such the determination of the appropriate sample size is one of the recurrent problems in statistical analysis. 603 respondents are needed and that becomes your sample size.
