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Web Calculator

Calculating power and sample size for study design

Note: The web calculator pages include links to JavaScript-based forms for easy calculation of power and sample size for study planning.

For an extensive list of alternative and more comprehensive sources of help, see for example: UCSF Biostatistics - Power and Sample Size Programs.

Using the web calculator, the following is possible:

Calculation of the power and sample size for proportions (relative frequencies) of two independent samples

Calculation of the confidence interval for the difference of two proportions

Comparison of the mean value with a reference value (t-test for one sample)

Comparison of means between two independent samples (t-test for two samples)

Comparison of a proportion (rel. frequency) to a reference value

Comparison of proportions (rel. frequencies) between two independent samples

Unmatched case-control studies