For a typical intervention review including quantitative data, standard effect measures will need to be chosen to compare studies. The next step usually involves determining whether statistical synthesis is possible and appropriate. This step entails determining whether the studies are sufficiently homogenous regarding clinical aspects, methodological characteristics, and statistical characteristics. Clinical and methodological heterogeneity are explored using clinical and methodological insight. Statistical heterogeneity is examined by visualizing the range of point estimates and 95% confidence intervals presented in forest plots and by calculating the I² statistic and/or Cochran Q, which determines if the results from each study are more different from each other than one would expect due to chance alone.