When and why is it necessary to use posthoc testsSolutionANO

When and why is it necessary to use post-hoc tests?

Solution

ANOVA test tells whether a researcher have an overall difference between groups, but it does not tell which specific groups differed – which post hoc tests do. Because post hoc tests are run to confirm where the differences occurred between groups, they should only be run when there is an overall significant difference in group means (i.e., a significant one-way ANOVA result). Post-hoc tests attempt to control the experiment wise error rate in the same way that the one-way ANOVA is used. Post-hoc tests are also termed as posteriori tests; which means tests that are performed after the event (the event in this case being a study).