“second variable, we find that Z = 2.103, p = .035. This value is larger than that obtained by the parametric test, p = .019.21 SUMMARY When analysts need to determine whether two groups have different means of a continuous variable, the t-test is the tool of choice. This situation arises, for example, when analysts compare measurements at two points in time or the responses of two different groups. There are three common t-tests, involving independent samples, dependent (paired) samples, and the one-sample t-test. T-tests are parametric tests, which means that variables in these tests must meet certain assumptions, notably that they are normally distributed. The requirement of normally distributed variables follows from how parametric tests make inferences. Specifically, t-tests have four assumptions: One variable is continuous, and the other variable is dichotomous.”