(To use this page, your browser must recognize JavaScript.)

Choose which calculation you desire, enter the relevant values (as decimal fractions) for p0 (known value) and p1 (proportion in the population to be sampled) and, if calculating power, a sample size. You may also modify alpha and the power, if relevant. After making your entries, hit the calculate button at the bottom.

Enter a value for p0:

Enter a value for p1:

Enter a value for alpha (default is .05):

Enter a value for desired power (default is .80):

The sample size is:

Reference: The calculations are the customary ones based on the normal approximation to the binomial distribution. See for example, Rosner, B., Fundamentals of Biostatistics (4th ed.), Section 7.10.3.

Acknowledgments: The JavaScript underlying this page uses normal quantile and probability functions taken from Jan deLeeuw's Web-based Statistics: The Study of Stability in Variation.