Systematic reviews encompass a variety of methods that involve gathering existing studies and research, then collectively analyzing them. This group of methodologies helps to identify larger conclusions about a body of knowledge, as well as identify gaps in that knowledge. These methods can also help answer research questions that are difficult to answer in a smaller, limited study.
Systematic reviews can be used to answer questions such as:
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was created by researchers around the world to standardize and improve the validity of systematic reviews and meta-analyses. These standards and recommendations are regularly updated. The latest version of the PRISMA Statement asks researchers to, among other things:
...and much more. The full PRISMA checklist is extensive, and can be viewed at the link below.
For this type of study, researchers will locate and use datasets from similar, smaller studies that match a pre-determined set of criteria. Criteria can include factors such as sample selection criteria, how recently the studies were conducted, the language of publication, and so on. The authors then use statistical methods to analyze the data from these studies to draw larger conclusions and commonalities.
This methodology generally includes a significant literature review, but also some direct data collection by the authors. The authors will then use both qualitative and quantitative methodologies to analyze their data.
This type of systematic review is the result of researcher efforts to determine how much (if any) information is available on a specific topic or research question, sometimes created as preparation for a larger systematic review.