When researchers use designs that call for multiple groups, the most commonly employed test is:

When a design compares more than two groups, the F-test used in analysis of variance is the most common choice.

The F-test compares the variance between groups with the variance within groups across all groups at once.

The Z-test suits large samples and a known population standard deviation, usually for one or two means.

The t-test for difference of means handles only two independent groups at a time.

The paired t-test compares two related measurements on the same subjects, again only two conditions.

Repeated t-tests across many groups inflate the Type I error, which the single F-test avoids.