The quality of the study is high, meaning we can be fairly confident in the study findings. The study finding is likely to be attributable to the program examined. This rating is reserved for findings from high quality randomized controlled trials with low attrition of sample members.

The quality of the study is moderate, meaning we can be somewhat confident in the study findings. However, factors other than the program examined could have influenced the study findings, and the study might not have fully accounted for those factors. We assign this rating to findings from randomized controlled trial studies that, because of flaws in the study (for example, high sample attrition), do not meet the criteria for the high rating but satisfy other design criteria. We also assign the moderate rating to study findings from well-executed quasi-experimental design studies.

The quality of the study is low, meaning we cannot have much confidence in the study findings. Factors other than the program examined could have influenced the study findings, and the study did not account for those factors. Study findings that do not meet the high or moderate ratings criteria receive the low rating.