The t-test is a statistical test used to compare the means of two different groups. It is particularly useful in hypothesis testing to determine if there is a significant difference between the means of the groups being studied. The null hypothesis typically states that there is no difference between the group means, while the alternative hypothesis suggests that a difference does exist ⁵.

There are three main types of t-tests: the one-sample t-test, the paired t-test, and the two-sample t-test. The one-sample t-test compares the mean of a single group to a known value. The paired t-test is used when comparing two related groups, such as measurements taken from the same subjects at different times. The two-sample t-test compares the means of two independent groups ⁵.

The t-test assumes that the sample data follows a t-distribution, which is similar to the normal distribution but has longer tails. This test is typically applied when the sample size is small (n < 30) and the population variance is unknown ⁴.