Meta-analysis

Systematic and quantitative examination of the results from different studies, pooling them so that robust conclusions can be reached and the nature of agreements or disagreements can be clarified and understood.  A important technique in meta-analysis is a funnel plot: a test for publication bias in meta-analyses in which the number of participants in each study is plotted against effect size, with an indication for such a bias being effect sizes that are larger for studies with small samples.  Meta-analysis should not be confused with metanalysis (i.e., forming a new word due to mistaking the boundary between existing words). 

See Effect size, Influence efficacy, Pictorial depth cues