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Research Guides

Public Health

Database Searching

Keyword Searching

Subject Headings

Keywords describe your topic in natural language, and can be combined in any number of ways.  Keyword searching is the most common approach to beginning the research process.

  • Keyword searching does not consider meaning or context of terms.  Homonyms (words with the same spelling and pronunciation, but different meanings) are particularly troublesome.
  • A database searches for keywords anywhere in a source's record (title, author name, abstract, subject heading, etc.), which often produces too many, too few, or irrelevant results.

Subject headings make-up a controlled vocabulary used by databases to describe content and organize sources.  Subject headings coalesce synonyms and like terms, topics, and concepts under a single term. 

  • Subject headings are pre-defined words, not natural language.  (Look for a Subjects or Thesaurus link in the database to reveal its list of subjects.) 
  • Subject headings usually produce very  relevant results.


Boolean Operators

  • Use AND to connect keywords and refine your search (retrieves sources with both terms)

  • Use OR to connect keywords and broaden your search (retrieves sources with either terms)

  • Use NOT to exclude a word e.g., Omega-3 fatty acids NOT Fish oils

  • *Use quotation marks to retrieve sources with a phrase in the exact order typed e.g., "Community health"

PubMed & MeSH

MeSH (Medical Subject Headings) is the National Library of Medicine's (NLM) controlled vocabulary.  NLM is the producer of MEDLINE, which is the primary component of PubMed.  MeSH terms are assigned to articles based on content.  When searching PubMed, we encourage you to use MeSH, as these terms will help you target your search.  

  • MeSH terms clarify context (topical and grammatical) 

  • MeSH terms include synonyms and related terms 

In PubMed, select MeSH from the search bar's drop-down menu, or select the MeSH Database link under More Resources to discover MeSH term(s).