Comparing Two Independent Samples, Sample Size Calculator

Expected detectable mean difference
Common population standard deviation
Level of significance
Desired power

Calculator to determine an appropriate sample size for detecting a difference between the means of two independent samples. Enter the relevant population values: The mean difference you want detect and the common standard deviation as well as the desired power (1 - type II error rate) and α (type I error rate). After making your entries, hit the calculate button at the bottom to calculate the sample size (assumed the same for each sample). The calculations are the customary ones based on normal distributions.

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