In response to these limitations, meta-analysis emerged as an alternative approach and has since become an important part of the toolkit for pooled data analysis (e.g., Cooper et al., 2009). In its simplest form, meta-analysis produces a weighted average effect size for a given association of interest across multiple studies based on summary statistics from each contributing study. Current applications of meta-analysis may also take into account characteristics of contributing studies (e.g., sample size, instrumentation differences) in deriving the weighted average effect size, providing more nuanced interpretations of the synthesized findings. Despite the many advantages of meta-analysis (see Cooper et al., 2009), a key limitation for certain pooled data analysis problems is their reliance on summary statistics derived from completed studies as the unit of analysis, restricting topics of inquiry to those questions that have already been addressed within individual studies.
