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Conducting a Literature Review

Developing a Search Strategy

A search strategy is an organized structure of key terms used to search a database. The search strategy combines the key concepts of your search question in order to retrieve accurate results.

Your search strategy will account for all:

  • possible search terms
  • keywords and phrases
  • truncated and wildcard variations of search terms
  • subject headings (where applicable)

Each database works differently so you need to adapt your search strategy for each database. You may wish to develop a number of separate search strategies if your research covers several different areas. 

It is a good idea to test your strategies and refine them after you have reviewed the search results.

This is a sample planner to develop your search terms from a PICO format

Simple chart with PICO as headings, and descriptions below


Identifying Search Terms

Once you have developed your research question or chosen your topic you can begin to brainstorm terms to use in your database search.

  • Brainstorm terms authors or indexers might use to describe your topic
  • Make a list of terminology and relevant terms to use in your search
  • Include synonyms or similar terms to combine using the Boolean operator OR
  • Search for controlled vocabulary in the databases i.e. search PubMed for MeSH terms

Combine the Elements of Your PICO Question with Boolean Operators

Boolean Operators (Using AND, OR NOT):

Boolean logic is a building block of many computer applications and is an important concept in database searching.  Using the correct Boolean operator can make all the difference in a successful search.


There are three basic Boolean search commands: ANDOR and NOT.

  • AND searches find all of the search terms.  For example, searching on dengue AND malaria AND zika  returns only results that contain all three search terms.  Very limited results.
  • OR searches find one term or the other.  Searching on dengue OR malaria OR zika returns all items that contain any of the three search terms.  Returns a large number of results.
  • NOT eliminates items that contain the specified term.  Searching on malaria NOT zika returns items that are about malaria, but will specifically NOT return items that contain the word zika.  This is a way to fine-tune results. Note:  sometimes AND NOT is used; serves the same function as NOT

Using Boolean Search with Exact Phrases:

If you're searching for a phrase rather than just a single word, you can group the words together with quotation marks.  Searching on "dengue fever" will return only items with that exact phrase.  

When to use Parentheses?

Think of your search in concepts, then put those concepts inside parentheses.  Different databases have different rules about combining searches.  To make sure you get the search you want, use parentheses - every database follows those rules.

Run a Preliminary Search

Look at titles and publication dates to decide which articles you want to look at in depth.

  • Select an article and begin the skimming and scanning process.
  • If the list has too many irrelevant results, consider selecting different keywords and revising your search.
  • If the list has too many results, consider setting date limiters or narrowing your results by searching phrases instead of keywords.
  • If the list has too few results, consider selecting different keywords