For practices, Study Reviewers analyze all of the eligible and applicable meta-analysis studies to determine whether there is evidence that the practice achieves its goal(s). The Study Reviewers use a standard Scoring Instrument to determine the quality of each meta-analysis and to determine the internal validity of each outcome within the meta-analyses. The quality rating for each meta-analysis is combined with the internal validity rating of each outcome and the statistical significance of the effect size to determine a final evidence rating. If there are multiple meta-analyses that assess a single outcome, the individual outcome ratings from each meta-analysis are then aggregated to determine the final rating for that outcome.
For practices, individual evidence ratings are assessed for each outcome. Therefore, a single practice may have multiple evidence ratings if it addresses multiple outcomes. That is, one practice may be rated “Effective” for achieving one outcome, and “Promising” for achieving another outcome.