What Is Heterogeneity?
Looking for the full method? Read the detailed guide: What Is Heterogeneity in Meta-Analysis?.
Heterogeneity refers to differences between studies in a meta-analysis, in their participants, interventions, methods or results, that go beyond what chance would produce. It can be clinical, methodological or statistical.
Example
Invented for teaching: Trials of an exercise programme include children and older adults, supervised and home-based sessions, and the effect estimates range widely. Statistical measures such as I² and a forest plot can highlight this variation.
Common misunderstanding
Heterogeneity is not an error to be removed or hidden. It is information: it may signal that studies are asking different questions or that effects vary across settings. A non-significant heterogeneity test does not prove that studies are similar.
Learn more
See What Is Heterogeneity in Meta-Analysis?
References and further reading
- Higgins JPT, Thomas J, Chandler J, et al., editors. Cochrane Handbook for Systematic Reviews of Interventions. Cochrane. Link
- Higgins JPT, Thompson SG. Quantifying heterogeneity in a meta-analysis. Stat Med. 2002;21(11):1539-1558. doi:10.1002/sim.1186
This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.