Rethinking Meta‐Analysis: Applications for Air Pollution Data and Beyond

Meta‐analyses offer a rigorous and transparent systematic framework for synthesizing data that can be used for a wide range of research areas, study designs, and data types. Both the outcome of meta‐analyses and the meta‐analysis process itself can yield useful insights for answering scientific questions and making policy decisions. Development of the National Ambient Air Quality Standards illustrates many potential applications of meta‐analysis. These applications demonstrate the strengths and limitations of meta‐analysis, issues that arise in various data realms, how meta‐analysis design choices can influence interpretation of results, and how meta‐analysis can be used to address bias and heterogeneity. Reviewing available data from a meta‐analysis perspective can provide a useful framework and impetus for identifying and refining strategies for future research. Moreover, increased pervasiveness of a meta‐analysis mindset—focusing on how the pieces of the research puzzle fit together—would benefit scientific research and data syntheses regardless of whether or not a quantitative meta‐analysis is undertaken. While an individual meta‐analysis can only synthesize studies addressing the same research question, the results of separate meta‐analyses can be combined to address a question encompassing multiple data types. This observation applies to any scientific or policy area where information from a variety of disciplines must be considered to address a broader research question.