Which test?

Table 1. Some common tests for simple comparisons and when they should be used.

	Characteristics of outcome variables
Purpose	Continuous, normal	Continuous, non-normal OR discrete	Categorical
Compare one mean with a population value/ Describe one mean	One sample z-test/ t-test	One sample z-test if the sample size is large	One sample z-test/ exact binomial test
Compare 2 independent groups	Independent samples z-test/ t-test	Mann-Whitney U/ Wilcoxon Sum of ranks	Chi-squared test or Normal approximation or Fisher’s exact test
Compare 2 paired/ matched groups	Paired t-test	Wilcoxon signed ranks test/ sign test	McNemar’s test
Compare 3 or more independent groups	One way Analysis of Variance	Kruskal Wallis test	Chi-squared test or ordinal chi-squared test
Compare 3 or more matched groups	Repeated measures Analysis of variance	Friedman test	Cochrane Q