Module 8.1: Subject Access

LIS 5043: Organization of Information

Dr. Manika Lamba

Introduction

What is a Subject?

A subject is . . .

a representation of the intellectual content of an information object,

or

its aboutness, topic, theme, expressed concepts or ideas, area of interest or knowledge.

Understanding Subjects

The traditional view of a subject . . .

is based on bibliographic conventions for representing textual objects

distinguishes between what an object is about and what an object is (i.e., subject description of intellectual content vs. physical description of container or package)

Understanding Subjects

The traditional view of a subject . . .

assumes an object has identifiable intellectual content

Yet subjects are difficult or impossible to identify for a few textual objects and most nontextual objects

Problems in Subject Description

  • Subjective interpretation based on ambiguous, emotional content

  • Domain expertise of person doing subject representation

  • How do our choices align with user’s choices of search terms?

  • Materials that don’t lend themselves to simple subject representation

Why Distinguish Subject from Physical Description?

  • To distinguish between work and text

  • To clarify representations of various kinds of subjects

  • To provide more access points for searching

  • To provide intellectual access versus bibliographic access

Representing Intellectual Content

Representing Physical Object

Representing Form

Usually considered subject description:

  • Literary forms: poetry, essays

  • Popular genre: romance (fiction), jazz (music)

  • Type of info: correspondence, bibliography, statistics

  • Organization of info: calendar, outline, dictionary

  • Style or technique related to purpose or audience: comedy, drama, persuasion

  • Style or technique related to time period: Baroque (music), Impressionism (painting)

Representing Format

Usually considered physical description:

  • Physical media format: book, video, photo, map

  • Artifact format: sculpture, figurine, vase, shirt

  • Communication mode: text, image, video, audio

  • Technical digital format: ASCII/text, HTML, .pdf, .gif

  • Version/part of work: edition, translation, chapter

Functions of Subject Descriptions

Subject descriptions serve to . . .

  • Organize document shelving for physical browsing and retrieval
  • Inform searchers about intellectual contents of documents
  • Provide consistency of representations
  • Assist in collection development and acquisitions
  • Assist in collection maintenance

Remember Bob? A bobble-head toy

Attributes for Bob?

Attributes for Bob?

Bob’s Record in the System

How Do We Represent Subject About…

Processes and Products

Subject Indexing

Subject indexing languages

Terms or vocabulary used to represent document content; access points for record retrieval

  • Varies from one index or system to next
  • May be assigned from authority control list: controlled vocabulary
  • May be extracted or derived from document text: natural language
  • May be free text or determined by the indexer/cataloger

User-defined/assigned descriptors (social classification, folksonomies, ontologies)

Controlled Vocabulary Indexing

  • Based on standardized or controlled vocabulary for describing concepts consistently

  • Terms are assigned to documents

  • Terms are in subject or descriptor field only

  • Searcher inputs only controlled vocabulary terms

Controlled Vocabulary Indexing

Subject Authority Control

Vocabulary control of index terms or subject headings

Subject Authority File or List

All terms in any controlled vocabulary

Examples: subject headings list, thesaurus, OCLC subject authority file

Subject Authority Files

Concepts

  • Subject authority files are databases or collections of subject authority records

  • Subject authority records contain controlled vocabulary representing subjects

  • Three kinds of subject authority files are subject headings, thesauri, and LC or OCLC’s authority file

Subject Headings

Subject Headings Lists . . .

  • Provide subject headings for cataloging and searching
  • Contain both single-concept and multiple-concept (precoordinated) terms
  • Indicate semantic relationships (see, BT, NT…)
  • Are used to assign a few terms to describe whole document

Subject Headings List Examples

Library of Congress Subject Headings (LCSH)

Sears List of Subject Headings

Medical Subject Headings (MeSH)

LCSH Example

Library of Congress Subject Heading

  • Syndetic Structure
    • Relationships
      • Equivalent (USE/USE FOR)
      • Hierarchical (BT/NT)
      • Associative (RT/RT)
      • See Also (SA) special instructions to use as subdivisions or to other groups of related headings
      • See (works like USE – directs user to other subjects to use, but these terms may not be included in the catalog) These terms may become authorized later.
  • Scope notes

LC Subject Headings

  • Types of LC headings
    • Single noun Skating
    • Noun preceded by adjective Administrative Law
    • Noun preceded by another noun used like an adjective Energy industries
    • Noun connected with another by a preposition Radioisotopes in cardiology
    • Noun connected with another by *and* Libraries and society
    • Noun followed by parenthetical qualifier Cluttering (speech pathology)
    • Phrase or sentence Show driving of horse-drawn vehicles
    • Inverted headings Education, Bilingual
    • Proper names headings (any name)
    • Geographic names Argentina
    • Genre/Topic terms Animated films

Thesauri

  • Provide descriptors for indexing and searching

  • Contain mostly single-concept terms

  • Indicate semantic relationships (BT, NT, RT. . .)

  • Are used to assign many terms to describe whole/partial document

Thesauri Examples

Thesauri

  • The ERIC Thesaurus of Descriptors
  • The Art and Architecture Thesaurus
  • The Medical Subject Headings of the National Library of Medicine

Other useful resource

  • Publications on thesaurus construction and use

Natural Language Indexing

  • Based on existing vocabulary of documents

  • Terms are extracted or derived from titles, abstracts, full text

  • Terms are in title, abstract, descriptor, full-text fields

  • Searcher inputs any term likely to occur in free text

Free Text

  • terms added at the discretion of the cataloger
  • do not come from a controlled vocabulary or from the words of the document
  • cataloger tries to match user’s terms (user warrant)
  • not a frequent practice
  • can be used in combination with controlled vocabulary or natural language indexing

.. and now User-Defined

  • has many labels (user-supplied, folksonomy, tagging, social classification)
  • is really not a new practice but one that has recently become the buzz on the Web with the emergence of blogs and media sharing sites like Blogger, Flickr, YouTube, etc.
    • researchers in image retrieval have explored this idea
    • researchers in organization of information, thesauri development, indexing, subject representation have also explored this idea
  • to date is being used to tag images, web pages, blogs, library catalogs, etc.
  • needs to be taken to the next level!!

Considerations When Choosing Terms

  • Attributes of documents and users

  • Record field that will contain the data

    • out of several potential kinds of subject fields
  • Domain

  • Scope

  • Specificity

  • Exhaustivity

Specificity and Exhaustivity

  • Specificity: extent to which index terms precisely represent the subject of the document. Can be general or more specific.
  • Exhaustivity: extent to which indexing represents all concepts in a document.
  • Considerations
    • Level and complexity of terms in subject area/discipline
    • Users’ vocabulary level
    • Terminology used in documents
  • Example
    • Specificity is high if detailed math topics covered, e.g., set operations
    • Exhaustivity is high if all math operations in textbook covered

Specificity and Exhaustivity

Is really a continuum

What About Diversity and Subject Access?

What are some of the issues of diversity when we discuss subject access?

  • Appropriate level for audience
  • Appropriate language to represent subject matter
  • Politically correct terms to represent race/ethnic populations
  • Assigning incorrect subject terms to prohibit access to collection’s objects