Evidence or Knowledge Synthesis

Avoid unnecessary duplication of effort. Search subject & protocol databases for published or registered synthesis protocols before starting your own synthesis.

Write a protocol—including methodology for all stages of the process—before commencing your synthesis. Developing search strategies, & setting criteria for including & excluding sources ahead of time, reduce your risk of bias & enhance synthesis reproducibility.

When designing your protocol, think about how a third party will assess the quality of your future published synthesis and the risk of bias in your methodology..

Save time by re-using other researchers' search strategies. Check protocols & published syntheses addressing similar questions, but note that quality of search strategies varies.

Also use filters or hedges posted on websites about meta-analysis, syntheses, & systematic reviews. When possible, use filters or hedges tested for sensitivity & precision. Web searches for filters or hedges will mostly retrieve search strategies on costs & economics, program evaluation, & research study type.

Before screening, remove duplicates from the full set of search results, keeping track of the number of references before and after de-duplication for entry in a PRISMA diagram.

Spreadsheet software like Microsoft Excel or Google Sheets suffices for small syntheses. More complex projects may require specialized tools.

All screeners should test the inclusion & exclusion criteria on sample citations before screening works for a synthesis. When more than 1 person will screen titles & abstracts (strongly recommended to minimize bias), decide in advance how to handle conflicting judgements on inclusion & exclusion of search results.

Are the data and/or results from the studies you're including valid? Check the quality of their methodology.

As you plan your own synthesis, think about how a third party will assess the quality of your future published synthesis and the risk of bias in your methodology.

Spreadsheet software like Microsoft Excel or Google Sheets suffices for small syntheses. More complex projects may require specialized tools.

Regardless of complexity, all team members should test the data extraction form before applying it to screened works:

• Do you need to add additional variables?
• Do you need to add additional codes within a variable?
• Do you need to clarify variable or code definitions for consistency in data entry?

Graphics include forest plots, funnel plots, & PRISMA diagrams