Ensuring your search is clear and reproducible is an integral part of any evidence synthesis review. PRISMA-S is a checklist to guide researchers through the search and to ensure its reprodicibility. This is a new guideline but continues to be adopted by more journals as a standard part of any evidence synthesis review.
When searching the literature for an evidence synthesis project, we want to aim for as comprehensive a search as possible. This means using both keywords (subjective terms, identified by article authors or that simply exist in the titles/abstracts) and Subject Terms (vocabulary that is controlled by each database used to index articles). Why both? Because there may not be an appropriate Subject Term for every topic and some newer articles have not yet been properly indexed, and therefore will not have a Subject Term attached.
Your liaison librarian can help you develop your search terms or navigate each database's controlled vocabulary.
These words connect your search terms to either narrow, broaden, or exclude results, as demonstrated in this graphical example.
i.e. therapy AND family
therapy OR counseling
therapy NOT coaching
If you have keywords that are a phrase rather than a single word, place the phrase in quotation marks to keep it together.
i.e. "Autism Spectrum Disorder"
Also called "adjacency operators," this allows you to specify how close your search terms should be to one another in the search results. The code for this operator varies by database. In EBSCO, N will find words within 5 words of each other.
i.e. gender N5 gap would still pick up gender pay gap or gender wage gap
If you have a word that has multiple possible endings, add a truncation symbol to the end of the root word. Most typically it is the asteriks sign, but can vary by database.
i.e. child* = child, children, children's, childhood
This is similar to truncation, but the variation exists within the word, rather than at the end. Again, the symbol can vary by database.
i.e. wom#n = woman, women
While most every database you will utilize operates its searching mechanism using Boolean Operators, it may have it's own specific syntax for how Keywords and Subject Terms are identified. Therefore, once you have written your first search strategy following the recommended syntax of one database (for example, PubMed), you then must translate it according to each of your other databases.
Cochrane has a helpful Database Syntax Guide that can assist with this process.
Even when we create a comprehensive search, some resources may still not be retrieved in our databases due to indexing issues or based on where they were published. When this occurs, conducting a search by hand is appropriate.
When handsearching remember that this is still a systematic review and that the search should be replicable. Handsearched results should still be meticulously documented and added to the PRISMA diagram.
Because systematic reviews aim to be comprehensive syntheses of the evidence, we must also look outside of traditional publishing venues for results. Grey Literature is material that is either informally published or unpublished. Examples include dissertations, conference proceedings, reports, data, etc.
You may already know some sources of grey literature in your discipline for you to search. Below are some examples of other databases and online resources in which to find these materials.