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Database Search Tips: Subject
Searching

What are Subject Headings?

Subject Headings can save you a lot of time and frustration by limiting to articles that are right on your topic. 

A subject heading is an assigned word (or phrase) used in a database to describe a concept. Search using this standardized word instead of keywords, so you do not need to wory about synonyms and spelling variations. 

 

  • Subject headings are assigned to each article by a subject specialist (indexer) who has read the article and determined its main subjects.They usually assign 10 -20 subject headings per article.
  • Subject searching is like using the index in the back of a book.  It directs you to the information on your subject.
  • Subject headings are also called controlled vocabulary terms, descriptors, MeSH terms (PubMed), CINAHL Headings, Index Terms, Tags, etc.
  • Most databases have their own unique subject headings, so when you search a different database, you will need to review their own subject headings.
  • Most databases provide a list (thesaurus) with definitions of their subject headings. Subject Headings are usually organized heirarchically, so you can browse for related, broader, & narrower subject headings.

Why Use Subject Headings?

Subject headings yield very precise, focused searches, so as a general rule of thumb, if there is an appropriate subject heading for one of your concepts--USE IT!

 

  • Subheadings: Some databases offer subheadings to use with subject headings, so you can focus the search even more.

 

  • Major Subject Headings: Some databases allow you to search subject headings as "Major", so you only retrieve articles with that subject heading as the main topic of the article

Please note: Not all databases have subheadings or allow 'major' headings. Check the Help section of the database for clarification.

 

Why use subject headings?

Keyword searches can results in a large number of irrelevant results.

 

  • The keyword may appear in the abstract, but it may not be the focus of the article. 
  • The keyword may be used in a different context than you intended. Example: If you search for "AIDS" (disease), your results may include hearing aids, audiovisual aids, clinical aides, teaching aids, etc.

 

Search by subject headings, keywords or both?

 Comprehensive searches usually use a combination of both keywords and subject headings

 

  • Keywords are great for the initial exploratory searches
  • If there is not a relevant subject heading for a concept, you will need to use your keyword list.
  • You can combine keywords & subject headings in one search.

 

Comparison Chart

How to Find Subject Headings?

Two ways to locate subject headings:

 

Method 1: Keyword Search Results

  1. Start with a keyword search
  2. Browse the results looking for relevant articles
  3. Look at the subject headings for each article that are usually listed near the abstract (note: newer articles may not have subject headings assigned yet)
  4. Revise your search using these terms

 

Example: PubMed subject headings (called MeSH terms)

Please note: Not all databases have subheadings or allow 'major' headings. Check the Help section of the database for clarification.

 

 

 

 

Method 2:  Browse Thesaurus

 

Browse the thesaurus (subject heading list), if available. 

Most thesauri include:

  • Subject heading definitions
  • Year the subject heading was added to the thesaurus
  • List of subheadings for that subject heading
  • Related terms
  • Hierarchy with broader and narrower subject headings (good way to find other possible search terms)
  • Some databases allow selecting & searching subject headings from within the thesaurus

 

 

 

Example: Subject heading entry in the MeSH thesaurus (PubMed)

 

 

 

 

 

How to Search with Subject Headings

Searching with subject headings

 

Method 1: Field Searching (see the Field Searching tab for an overview)

  • When searching with subject headings, there are 3 field search options to try--providing broader and narrower results.
  • Searching is a trial and error process, so try the different options and evaluate your results to determine if you need to narrower/focus your searches.  

 

Default Field Search: Broader search results

The default search in most databases automatically searches the Subject Headings field along with the Title and Abstract fields, so this will give you all the articles with the search terms listed in any of these three fields.

  1. Enter the subject terms in the search box
  2. Click on "Search"

Subject Heading Field Search: More focused search results

  1. Enter the search terms in the search box
  2. Use the drop-down menu next to the search box and select "Subject Heading"  (This may vary slightly by database. If you don't see the drop-down boxes, go to the Advanced Search screen)
  3. Click on "Search"

Major Subject Heading Field Search: Very focused search results

  1. Enter the search terms in the search box
  2. Use the drop-down menu next to the search box and select "Major Subject Heading" (This may vary slightly by database. If you don't see the drop-down boxes, go to the Advanced Search screen)
  3. Click on "Search"

 

Example of the field options in CINAHL

 

 

 

Method 2: Search from the Thesaurus

 

This method is only available in a few databases. Check the Help section of the database for details.

  1. Go to the thesaurus
  2. Find the relevant subject heading
  3. Add the subject heading to the thesaurus' search box 
  4. Select any appropriate subheadings and/or designate major subject heading (Be very careful here--you do not want to narrow down your search too much. Only use subheadings & major when you are having a hard time focusing your search)
  5. Click on Search