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PubMed

This guide includes information on PuBMed and search tips.

Precision vs. Recall

• Precision = Relevant Records Retrieved

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               All Records Retrieved

• Recall = Relevant Records Retrieved

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        Relevant Records in Database

When searching a database, try to balance precision (returns less search results but more of them relevant) and recall (returns more search results, trying to find all relevant results in database).

Boolean Operators

•AND – Tells database that ALL search terms must be present in results. Used to narrow results (increase precision).
•OR – Tells database that ANY of the search terms can be present in results. Used to broaden results (increase recall).
•NOT – Tells database that NONE of the search terms should be in results. Used to narrow results (increase precision).
 
       

Search Fields

•Search fields are defined data fields for a database record, like Title, Author, Publication Date, etc.
•Most databases offer some type of fielded searching option.
•Example of fielded search in PubMed (searching within Author and Title fields):
–Smith J[au] AND neoplasm[ti]
 
                         
 

Indexes

•An index in a database is a list of all terms listed under a specific field in the database (like an author index).
–The index also usually lists how many records the term appears in.
 

Search History

•Many online search tools (including PubMed) keep track of all searches that you’ve recently run in a search history.
•Some online search tools (including PubMed) also allow you to combine past queries using Boolean Operators.
                

Controlled Vocabulary

  • A controlled vocabulary in a database provides consistent terminology for describing database records.
  • Medical Subject Headings (MeSH) are an example of a controlled vocabulary for the MEDLINE database.
  • Example: Articles about cancer in MEDLINE would be indexed under the MeSH term “Neoplasms”.