Among sample size, degrees of freedom, effect size, significance level, and power, one and only one can be left blank.

Provide the number of participants. Multiple sample sizes can be provided in two ways. First, multiple sample sizes can be supplied separated by white spaces, e.g., 100 150 200 will calculate power for the three sample sizes. A sequence of sample sizes can be generated using the method s:e:i with s denoting the starting sample size, e as ending sample size, and i as the interval. For example, 100:150:10 will generate a sequence 100 110 120 130 140 150.

By default, the sample size is 100.

Degrees of freedom for the chi-square test

The effect size to be used. The effect size can be determined using the effect size calculator.

The significance level (Type I error rate) for power calculation with the default 0.05.

The power of the test.

Whether to generate the power curve.

A note (less than 200 characters) can be provided to provide basic information on the analysis.

On the effect size page, input the population model first with parameters (including the path to be estimated for power). Then in the restricted model field, input the model without the path to be estimated. Finally, click the “Calculate” button. The effect size is shown at the bottom of the page.

An example is given below