One commonly used form of evidence synthesis is a systematic review. This table compares a traditional literature review with a systematic review:
| Traditional Literature Review | Systematic Review | |
|---|---|---|
| Review Question/Topic | Topics may be broad in scope; the goal of the review may be to place one's own research within the existing body of knowledge, or to gather information that supports a particular viewpoint. | Starts with a well-defined research question to be answered by the review. Reviews are conducted with the aim of finding all existing evidence in an unbiased, transparent, and reproducible way. |
| Searching for Studies | Searches may be ad hoc and based on what the author is already familiar with. Searches are not exhaustive or fully comprehensive. | Attempts are made to find all existing published and unpublished literature on the research question. The process is well-documented and reported. |
| Selecting Studies | Clear reasons for why studies were included or excluded from the review are often lacking. | Reasons for including or excluding studies are explicit and informed by the research question. |
| Assessing the Quality of Included Studies | Study quality or potential biases in study design are often not considered. | Risk of bias of individual studies and overall quality of the evidence, including sources of heterogeneity between study results, are systematically assessed. |
| Synthesizing Existing Research | Conclusions are more qualitative and may not be based on study quality. | Conclusions are based on quality of the studies and provide recommendations for practice or to address knowledge gaps. |
Systematic reviews usually require a team of at least three researchers if not more. Once the authors and any additional support personnel are assembled, a systematic review typically will include the following steps :
The following tabs (also linked above) describe each evidence synthesis step in more detail, as well as provide resources and guidance.