Find Minimum Sample Size Calculator. Accuracy is determined by the following three variables. This calculator uses a number of different equations to determine the minimum number of subjects that need to be enrolled in a study in order to have sufficient statistical power to detect a treatment effect.
If youd like to see how we perform the calculation view the page source. Discover how many people you need to send a survey invitation to obtain your required sample. For example if you use a confidence interval of 4 and 47 percent of your sample picks an answer you can be sure.
This equation is for an unknown population size or a very large.
If you are dealing with a population mean instead of a population proportion you should use our minimum required sample size calculator for population mean. If you want to find instead a confidence interval for the mean please use this confidence interval calculator. Where N is the population size r is the fraction of responses that you are interested in and Zc100 is the critical value for the confidence level c. The confidence interval is being reported in the form x.
