What defines the methodological approach of a systematic review?

The methodological approach of a systematic review is defined by following predefined protocols. This means that a systematic review is conducted using a structured and transparent methodology that has been established prior to the review process. These protocols typically include the specific criteria for including or excluding studies, methods for literature search, data extraction processes, and techniques for assessing the quality of the studies considered. This rigorous approach ensures that the review is replicable and minimizes bias, allowing for a reliable aggregation of evidence.

In contrast, random participant selection refers more to the methodologies used in primary research studies, while ignoring past research findings goes against the purpose of a systematic review, which is to examine all relevant literature systematically. Lastly, while qualitative data can be included, a systematic review does not exclusively focus on qualitative data; it can encompass both qualitative and quantitative research depending on the topic. Thus, the adherence to predefined protocols is what fundamentally distinguishes a systematic review as a comprehensive and objective synthesis of existing research.