A single study conducted to examine an issue will not usually establish definitive conclusions. It takes the accumulation of results across studies to begin to establish facts that can be then used to either validate a theory or formulate a new one. For example, many studies have been conducted to examine the relationship between the theoretical concept self-efficacy and academic achievement. That is, does a person's belief in his or her ability to perform academic tasks such as taking tests and completing homework assignments have an impact on academic achievement (e.g., grades, test scores)?

The traditional way to accumulate knowledge across these studies was to conduct a review of the literature. A researcher read all the published studies on the topic and then wrote a narrative ...