Hypothesis tests

This page is intended as an introduction to some commonly used basic hypothesis tests. Before using any of these, it is important that the concepts behind hypothesis testing are understood. These concepts are explained on this page.

Hypothesis tests are very commonly used in epidemiological investigations, and a wide number of tests are available. These can be classified into groups according to the data types in question, according to whether a specific underlying distribution is assumed when performing the test (in which case, the test is known as a parametric test), and according to whether or not the data are matched or independent (i.e. whether comparisons are being made at the individual level or the group level).

Comparing a qualitative variable between different groups

Chi-square test

Fisher's exact test

Comparing a quantitative variable between two groups

t-test

Mann-Whitney U test

Comparing a quantitative variable between more than two groups

ANOVA

Kruskal-Wallis

Comparing a categorical outcome between matched observations

McNemar's chi-square test

Comparing a quantitative outcome between matched observations

Paired t-test

Comparing two quantitative outcomes between matched observations

Pearson's correlation coefficient

Spearman's rank correlation coefficient