The two sample test of proportions compares the proportions of two arms of a study, \(p_1\) and \(p_2\).

Note: There does not exist a closed form formula for the power of the bionomial test so this calculator uses simulations to solve for power. For large sample sizes, large sample theory can be used.

Power Calculation Parameters

To input multiple values, seperate them by a comma.

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Power Calculation Explanation

Solve For

The unknown you are interested in solving for.

N

The sample size used to test the hypothesis.

Alpha

The \(\alpha\) (Type I error rate) level of the hypothesis test.

Power

The power (1 - Type II error rate) of the hypothesis test.

P (Arm 1)

The estimated proportion from arm 1 (\(p_1\)). If you are comparing a difference in proportions to zero, set this value to the difference.

P (Arm 2)

The estimated proportion from arm 2 (\(p_2\)). If you are comparing a difference in proportions to zero, set this value to zero.