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Systematic Review Process: best practices

Steps to a successful search strategy

Basic search tips

Boolean Operators are simple words used as conjunctions to combine or exclude keywords in a search, resulting in more focused and productive results.  Using these operators can greatly reduce or expand the amount of records returned. Boolean operators are useful in saving time by focusing searches for more 'on-target' results that are more appropriate to your needs, eliminating unsuitable or inappropriate.


Use OR to broaden search results. This expands the search to include all records containing either concept. Think of using OR in terms of synonyms or related terms.


AND will narrow your search results to include only relevant results that contain your required keywords.


Use NOT in a search to exclude words from your search and narrow your search, telling the database to ignore concepts that may be implied by your search terms.


Databases follow commands you type in and return results based on those commands.  Be aware of the logical order in which words are connected when using Boolean operators: 

  • Databases usually recognize AND as the primary operator, and will connect concepts with AND together first.
  • If you use a combination of AND and OR operators in a search, enclose the words to be "ORed" together in parentheses.

Check the "The Boolean Machine by Rockwell Shrock"

Advanced search options are a set of filters offered by most search engines on the web. They narrow the scope of a search query to eliminate irrelevant information to help you find the exact content you're looking for.

If your search returns few or no records, you might have more success if you can think of alternative search terms. This can include:

  • other terms related to your topic
  • synonyms (words with the same meaning)
  • different word endings (singular and plural forms, for example)
  • different spellings (UK versus US spelling, for example)