Select the statistical test appropriate for your problem

In Step 1, the statistical test is chosen using the distribution-based or the design-based approach. G*Power 2 users probably have adapted to the distribution-based approach. This approach is described first.

Distribution-based approach to test selection

First select the family of the test statistic (i.e., exact, F-, t-, χ², or z-test) using the Test family menu in the main window. The Statistical test menu adapts accordingly, showing a list of all tests available for the test family.

Example

For the two groups t test, first select the t family of distributions.

Then select Means: differences between two independent means (two groups) in the Statistical test menu.

Design-based approach to test selection

Alternatively, one might use the design-based approach. With the "Tests" pull-down menu in the top row it is possible to select

• the parameter class the statistical test refers to (i.e., correlations and regression coefficients, means, proportions, or variances), and
• the design of the study (e.g., number of groups, independent vs. dependent samples, etc.).

The design-based approach has the advantage that test options referring to the same parameter class (e.g., means) are located in close proximity, whereas they may be scattered across different distribution families in the distribution-based approach.

Example

In the Tests menu, select Means, then select Two independent groups" to specify the two-groups t test.