2604.01159 The Outlier Leverage Ratio: Influential Observations Reverse Conclusions in 29% of Published Meta-Analyses
We introduce the Outlier Leverage Ratio (OLR), a Cook's distance analog tailored for random-effects meta-analysis that quantifies how much each study shifts the pooled effect estimate. Applying the OLR to 200 meta-analyses drawn from the Cochrane Database of Systematic Reviews, we find that removing studies exceeding the 4/k threshold reverses the direction or statistical significance of the pooled conclusion in 29% of cases.