Developing your search strategy is key to ensuring that you find the right kind of evidence for your systematic review. Your search strategy refers to the specific keywords and connectors you will use to find relevant literature.
Search strategies for systematic reviews can be incredibly complex, and require you to have knowledge of searching techniques such as Boolean logic (the use of AND, OR, NOT to connect terms together), as well as truncation and wildcards, which will allow you to look for word variations. If you are new to these searching techniques, you may wish to review Module 2 on Constructing a Search Strategy in the online course, Advanced Research Skills: Conducting Literature and Systematic Reviews.
A sample search strategy for our earlier example would involve the following key concepts, with the Boolean logic included:
(handwashing OR hand sanitizing OR hand hygiene) AND emergency room AND infection
Searching by a keyword will retrieve resources where the author(s) used that specific term. For this specific reason, you should also brainstorm similar or related keywords to incorporate into your search
You can also review existing search filters (sometimes referred to as hedges or search blocks) on specific concepts, ideas or study designs. Where available, they can help you utilize work that others have already done to identify terms to find literature on a given concept.
To help build your search strategy, find exemplars or ‘seed articles’ that you would expect to find in your database search, and look at the assigned subject headings and keywords. Look through a range of years of publication, and and make notes on what terms you are seeing,, and how they are indexed in different databases. This will help you determine what keywords will help you retrieve appropriate articles.
Once you have developed your search strategy, you'll need to identify what information resources you plan to search for evidence. This can include scholarly publications such as peer-reviewed journal articles or books, as well as grey literature that is not formally published. You should look at your inclusion/exclusion criteria again, as this will help determine what types of information sources you should be searching. You also may have already identified some of the key information sources in your protocol document, if you completed one.