The goal of evidence synthesis searches is to identify all relevant studies on a topic. Therefore, these searches are typically quite extensive. It is necessary, however, to strike a balance between striving for comprehensiveness and maintaining relevance when developing a search strategy. Increasing the comprehensiveness (or sensitivity) of a search will reduce its precision and will retrieve more non-relevant articles.
It is also important to document your search strategy in order to increase transparency and the reproducibility of your searches.
Look for existing evidence syntheses or protocols on your topic (or a similar topic). This will allow you to:
Below are some good places to start:
Next, do a quick search in PubMed (or another relevant academic research database) to get a better sense of how much relevant literature is available on your research question for you to conduct your evidence synthesis.
At this stage, you can save a few of the relevant studies you know you want to include in your final review (between 3 and 10), which will come in handy as you create and test your final comprehensive search strategy.
The goal is to maximize recall and precision while keeping results manageable. Recall (sensitivity) is defined as the number of relevant reports identified divided by the total number of relevant reports in existence. Precision (specificity) is defined as the number of relevant reports identified divided by the total number of reports identified.
Things to consider when creating a comprehensive search: