Which aspect of systematic reviews helps determine the scope and relevance of included studies?

The aspect of systematic reviews that plays a critical role in determining the scope and relevance of included studies is the inclusion and exclusion criteria. These criteria are predefined guidelines that specify which studies will be considered for the review and which will be excluded based on certain parameters. This ensures that the studies selected align closely with the research question and objectives of the review, thus providing a focused and relevant body of evidence.

Inclusion criteria may involve factors such as study design, population characteristics, interventions, and outcomes of interest, while exclusion criteria help eliminate studies that might introduce bias or unrelated information. By carefully outlining these criteria, researchers can maintain consistency and transparency in the review process, enhancing the validity of the findings.

Other options, while important in their own right, do not directly define the scope and relevance of studies in the same way. For example, outcome measures pertain to the specific results that are being evaluated, sampling methods focus on how participants are selected, and effect size calculations deal with quantifying the magnitude of an effect observed in the studies. Each of these elements contributes to the overall understanding of the studies in a systematic review, but the inclusion and exclusion criteria are essential for establishing a clear framework for what studies are deemed relevant.