12. t-tests

The t-test looks at difference in means between two things (e.g., groups, time, observations). There are three different types of t-tests:

1. The one-sample t-test tests how the sample mean relates to the population mean.

2. The independent t-test has two independent groups. The participants or things in group 1 are not the same as the participants or things in group 2. This is a between-subjects design in which different participants are in the two groups.

3. The dependent t-test has dependent or paired data. The dependent variable is measured at two different times or for two different conditions for all participants or things. This is a within-subjects design in which case the same participants are in both groups.