Planning your search
The planning phase of developing, testing, and revising your search queries is crucial to the success of the systematic review.
In designing your search of the literature, you should consider:
- identifying the sources (i.e. databases) to search
- gathering a ‘sample set’ of references
- having a comprehensive list of search terms
- doing a ‘test run’ of your search queries
- revising your search strategy (if needed)
Do you have a set of relevant papers already that you want to include in your systematic review?
It is useful to build a ‘sample set’ of relevant references before you develop your search strategy. The ‘sample set’ may include:
- key papers recommended by your supervisor
- references used in similar systematic reviews
The ‘sample set’ of references will enable you to:
- help identify relevant search terms
- test that your search strategy will retrieve these references (and subsequently other relevant references on your research topic)
Developing, testing, and revising your search strategy
The search strategy needs to include a detailed list of search terms for each concept to ensure all relevant studies are captured for the review. Search terms will be made up of keywords or phrases, as well as database subject headings. Each database uses a different criterion to classify articles, so the subject headings will differ between them.
When using multiple databases, you are likely to encounter a large volume of resources. When planning your searches, you should continually adjust search terms and/or selection criteria in order to make sure you have a comprehensive body of references.
It is recommended that you test your search terms to determine if all the subject headings and words/phrases will return useful results. Test your search strategy in a key database. Does it retrieve any papers from your ‘sample set’ that are contained in that database? Are the results of the search relevant to your topic? What proportion are irrelevant? Identify any terms that are retrieving large numbers of irrelevant papers.
Documenting your search
It is essential that you thoroughly document your search process in enough detail to ensure that it can be reported correctly in the review.
For each database search you conduct, you should record:
- the date the search was run
- the name of the database
- the name of the database provider (e.g. ProQuest or EBSCO)
- your search strategy – include the keywords you used and how these were combined in the search
- any filters or limitations used, such as years, language, etc.
- the number of studies identified