What is the primary focus when assessing heterogeneity in a meta-analysis?

The primary focus when assessing heterogeneity in a meta-analysis is the variation between studies. Heterogeneity refers to the degree of inconsistency or variability in the results of different studies included in the meta-analysis. Evaluating this variation is crucial because it impacts how the results of the studies can be interpreted collectively. If the studies show substantial difference in their results, it might suggest that the underlying effects differ due to various factors like differences in populations, interventions, or methodologies.

Understanding the variation helps researchers determine whether it is appropriate to pool the results together into a single estimate of effect or whether the differences warrant a more cautious interpretation. Heterogeneity can be quantified through statistical tests, such as the I² statistic or Cochran’s Q, which provide insight into the degree of inconsistency among study outcomes. Recognizing and addressing heterogeneity is essential for ensuring that the conclusions drawn from a meta-analysis are valid and applicable across different settings and populations.