A re-evaluation of fixed effect(s) meta-analysis

• Published in: Journal of the Royal Statistical Society. Series A, Statistics in society Vol. 181; no. 1; pp. 205 - 227
• Main Authors: Rice, Kenneth, Higgins, Julian P. T., Lumley, Thomas
• Format: Journal Article
• Language: English
• Published: Oxford John Wiley & Sons Ltd 01.01.2018; Oxford University Press
• Subjects: Analysis; Common effect; Fixed effect; Fixed effects; Literature reviews; Meta-analysis; Meta‐regression; Random effect; Regression analysis; Statistical analysis; Statistical methods; Weighting
• ISSN: 0964-1998; 1467-985X
• DOI: 10.1111/rssa.12275

Meta-analysis is a common tool for synthesizing results of multiple studies. Among methods for performing meta-analysis, the approach known as 'fixed effects' or Inverse variance weighting' is popular and widely used. A common interpretation of this method is that it assumes that the underlying effects in contributing studies are identical, and for this reason it is sometimes dismissed by practitioners. However, other interpretations of fixed effects analyses do not make this assumption, yet appear to be little known in the literature. We review these alternative interpretations, describing both their strengths and their limitations. We also describe how heterogeneity of the underlying effects can be addressed, with the same minimal assumptions, through either testing or meta-regression. Recommendations for the practice of meta-analysis are given; it is hoped that these will foster more direct connection of the questions that meta-analysts wish to answer with the statistical methods they choose.