Find Sample Size Calculator. Sample sizes can also be calculated for clinical trial designs for evaluating superiority non-inferiority and equivalence. Discover how many people you need to send a survey invitation to obtain your required sample.
This is the minimum sample size you need to estimate the true population. Yep thats a lot of statistics jargon. You can also find the level of precision you have in an existing sample.
If the sample proportion is close to 0 or 1 then this approximation is not valid and you need to consider an alternative sample size calculation method.
A free on-line program that calculates sample sizes for comparing two independent means interprets the results and creates visualizations and tables for evaluating the influence of changing input values on sample size estimates. Note that this sample size calculation uses the Normal approximation to the Binomial distribution. This can be done using the online sample size calculator above or with paper and pencil. Choose the required confidence level from the dropdown menu Input the margin of error.
