Definition: A specialized subset of systematic reviews, meta-analysis is a statistical technique for combining the findings from disparate quantitative studies and using the pooled data to come to new statistical conclusions. Not all systematic reviews include meta-analysis, but all meta-analyses are found in systematic reviews.
Aim: To synthesize evidence across studies to detect effects, estimate their magnitudes, and analyze the factors influencing those effects.
Strengths: Combines individual studies to determine overall evidence-based strength. Conclusions produced by meta-analysis are statistically stronger than the analysis of any single study, due to increased numbers of subjects, greater diversity among subjects, or accumulated effects and results.
Drawbacks/Limitations: Combining data from disparate studies produces misleading or unreliable results. For a meta-analysis to be valid, all included studies must be sufficiently similar.
Source: TARG Bristol. (2017, November 13). A three minute primer on meta-analysis [Video]. YouTube. https://www.youtube.com/watch?v=i675gZNe3MY