Table 1.

Types of Statistical Tests

Goal of Analysis	Is there a difference between the variables in two different groups? (H0: There is no difference between the means, medians, or distributions in the populations.)		Is there an association or relationship between two variables in the population? (H0: There is no association between the variables.)
Type of Data	Continuous			Categorical
Parametric	Unpaired Student’s t-test†	Paired Student’s t-test†	Pearson correlation coefficient	None.
Nonparametric	Wilcoxon rank- sum test*†‡	Wilcoxon signed- rank test†‡	Spearman’s correlation coefficient ‡	Pearson’s Chi Square Test of Independence & Fisher’s exact test

^*The Wilcoxon rank sum test is also known as the Mann-Whitney U test.

^†The unpaired Student’s t-test and the Wilcoxon rank-sum test involve unmatched pairs of data. In contrast, as the name suggests, the paired Student’s t-test and its counterpart, Wilcoxon signed-rank test, involve matched pairs.

^‡These non-parametric tests may involve either ordinal or continuous data.