Evidence guide
What Is a Meta-analysis?
A meta-analysis combines numerical results from multiple studies to estimate an overall effect.
The promise
Pooling can improve precision and reveal patterns too small for individual studies.
The trap
A precise average can still be misleading when studies measure different things, contain bias or omit unpublished negative results.
Read beyond the diamond
Look at heterogeneity, study quality, publication-bias checks, sensitivity analyses and whether the review protocol was registered before results were known.
A practical reading checklist
- Was the search comprehensive?
- Were weak studies separated from strong ones?
- How different were the included studies?
- Did conclusions change in sensitivity analyses?