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What is the Apply Equivalent Subjects expander?

The Apply Equivalent Subjects expander uses mapped vocabulary terms to add precision to unqualified keyword searches. (An unqualified keyword search is a general search that does not specify a field to search, such as title, subject or abstract.)

Mapped vocabulary terms come from multiple high-quality vocabularies used for indexing content. These terms identify concepts used in subject indexing. Popular searches from EBSCO search logs are also mapped to these concepts to increase opportunities for added precision in recall and relevance ranking.

Users generally do not know the specific vocabulary terms used by different publishers to index content. Often users enter popular terms when searching, or they enter terms used by one publisher for subject indexing but not another publisher to index similar content. This can lead to search results that don't include relevant records. It can also lead to poor relevance ranking on some high-quality records because the searched terms don't exactly match the subject terms on the high-quality records.

With the Apply equivalent subjects expander ON, when a user’s search term matches a known concept, the search is expanded to include the exact terms for that concept in the mapped vocabularies. Records that match the concept, (i.e., contain the mapped terms in the subject field), receive a relevance-ranking boost.


  • User searches: workplace injury
  • The search term workplace injury maps to the concept Work-related injuries
  • The concept Work-related injuries maps to the following subject-indexed concepts in different vocabularies used on different databases:
    • occupational injuries
    • occupational-related injuries
    • work-related injuries
  • The user's search gets expanded to include the concepts above for the specific databases that have records subject-indexed with those concepts.

Mapped Vocabularies:

The vocabularies for the databases below are mapped for equivalent subjects to precisely search and retrieve content from subject-index providers. You need to subscribe to databases from subject-index providers with mapped vocabularies and have the databases on your profile in order to benefit from equivalent subjects expansion.

Abstracts in Social Gerontology EconLit Library Literature & Information Science Index (H.W. Wilson)
Academic Search Databases Education Abstracts (H.W. Wilson) MasterFILE
AgeLine Education Research Complete MathSciNet
AGRICOLA Education Source MEDLINE (MeSH)
Alternative Press Index Engineering Source Middle Eastern & Central Asian Studies
America: History & Life Environment Index MLA International Bibliography
Anthropological Index Online ERIC Music Index, The
Anthropological Literature Family Studies Abstracts National Criminal Justice Reference Service Abstracts
Anthropological Plus Family & Society Studies Worldwide New Testament Abstracts
Applied Science & Technology Index (H.W. Wilson) Film & Television Literature Index NTIS (National Technical Information Service)
Applied Science & Technology Source FSTA - Food Science and Technology Abstracts Old Testament Abstracts
Art & Architecture Complete Gender Studies Database OmniFile (H.W. Wilson)
Art Abstracts (H.W. Wilson) GeoRef Petroleum Abstracts
Art Source HeinOnline Political Science Complete
ATLA Catholic Periodical and Literature Index Hospitality & Tourism Index
ATLA Religion Database Historical Abstracts PubMed (MeSH)
Bibliography of Native North Americans Humanities Abstracts (H.W. Wilson) Race Relations Abstracts
Biological & Agricultural Index Plus (H.W. Wilson) Humanities International Index Reader’s Guide to Periodical Literature (H.W. Wilson)
BIOSIS Previews Humanities Source Sears List of Subject Headings (H.W. Wilson)
Business Source Databases Index to Jewish Periodicals Social Sciences Abstracts (H.W. Wilson)
CAB Abstracts Index to Legal Periodicals and Books (H.W. Wilson) Social Work Abstracts
CINAHL Databases International Bibliography of Theatre & Dance SocINDEX
Communication & Mass Media Complete L’Annee Philologique Urban Studies Abstracts
Communication Abstracts Left Index, The Violence & Abuse Abstracts
Communication Source Legal Source Women's Studies International
Criminal Justice Abstracts LGBT Life  
Dentistry & Oral Sciences Source Library & Information Science Source  

Important points to note:

  • Expansions are limited to unqualified keyword searches. This means that if you use specific search tags (field codes) in your search, then equivalent subject expansions will not apply to the search terms preceded by a search tag.

  • Not every search gets expanded to equivalent subjects. When Apply equivalent subjects is ON, it doesn't mean every search gets an expansion; the search has to match a concept in order to expand to equivalent subjects.

  • Not every database is searched with equivalent subjects. When a search matches a concept, it doesn't mean every databases is searched with the concept expansion; the expansion only applies to searches against databases that use the mapped vocabularies.

  • Not every field is searched with equivalent subjects terms. When a search matches a concept, only a specific subject field is searched for the concept; the expanded terms are not searched for in the title or abstract or any other field.

  • Because the Apply equivalent subjects expander is customizable by administrators using EBSCOadmin, this expander may have a different label when displayed on EDS or EBSCOhost.

As with other expanders, Apply equivalent subjects can be turned ON or OFF in the user interface on the Advanced Search page and on the Search Options page.

The default setting (ON/OFF) for Apply equivalent subjects can be configured by administrators using EBSCOadmin. To modify the default setting, see: How do I customize how expanders appear using EBSCOadmin?


See also:

Using Expanders to Broaden Your Search