STATISTICAL SAMPLE SIZE CALCULATOR

Differences in Proportions

BETA VERSION

This calculator has been created to aid researchers in determining the adequacy of their sample sizes and resulting statistical power. Calculations are based on a normal curve test on the arcsine transformation of the proportions. Enter the data in the forms below, following three steps:

1. Enter data into all but one of the fields below. Any variable that is left open will be calculated. If you need help about what needs to be entered into a field, click the label button adjacent to the field.

2. Determine the number of "tails" of the exeriment by using the pull down menu. Click the help button next to the pull down menu for additional information.

3. Click the calculate button to determine the unknown field.

Is the experiment One-Tailed or Two-Tailed?

Once the variables are entered, click the button below to calculate the unknown quantity

Houle T.T, Penzien D.B, Houle C.K. "Statistical Power and Sample Size Estimation for Headache Research: An Overview and Power Calculation Tools"