Each year, researchers publish millions of new scientific articles. Given the large amount of information, it is hard to find out what is already known about any given health topic.
It is important to look at existing evidence before starting a new research project, or when considering a new policy change.
Evidence synthesis (also known as knowledge synthesis) gathers information on a topic. This allows us to see the “big picture” and identify any gaps.
Evidence syntheses can help to:
- Bring together research findings from many studies
- Find gaps or biases in the available information
- Identify the need for more research or to improve the quality of research
- Provide a background or context for future research
There are many different kinds of evidence syntheses. Some examples include literature reviews (academic and/or grey literature), background summaries, evidence inventories or bibliographies, systematic reviews, and scoping reviews.
Most evidence syntheses have similar steps:
- Develop a research questions
- Establish clear criteria for including or excluding information
- Search information sources to identify all studies that could be relevant
- Use the inclusion and exclusion criteria to decide what information to include
Some types of evidence synthesis (like systematic reviews) have one or two additional steps:
- Assess the quality of the information
- Summarize and/or analyze the information as a whole