Module 6a: Intro to Controlled Vocabularies, Taxonomies and Classification

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Module 6a Intro to Controlled Vocabularies,
Taxonomies and Classification

• IMT530 Organization of Information Resources
• Winter 2007
• Michael Crandall

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Module 6a Outline

• Where we are
• Controlled vocabularies
• Types of controlled vocabularies
• Tagging
• Overview of building vocabularies

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Recap

• We looked at the indexing process to see how
  controlled vocabularies can be used to enhance
  access to information
• Different methods of indexing provide different
  results
• Need to decide on your approach based on an
  analysis of your business objectives, the user
  needs, and the domain
• A combination of automatic and human indexing is
  often the best solution

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Overview of Subject Representation

• Subject analysis
• a technique used to determine the subject(s)
  and disciplinary context exemplified by an object
• Subject indexing
• a technique through which subject terms (words,
  taxonomic categories, or notation) are added to
  an object representation to describe the subject
  content of the object
• Controlled vocabularies
• standards containing controlled subject terms
  (words, taxonomic categories, or notation) used
  in the indexing process

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Controlled Vocabulary Definition

• A controlled vocabulary is a list of terms (words
  or phrases) or codes (notation) used for indexing
• Almost always, controlled vocabularies show
  relationships among terms

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Purpose of Controlled Vocabularies

• Specific Purposes
• To provide access to content by subject, through
  providing hierarchical and associative
  relationships and synonym control for the terms
  used in the domain
• Increase precision in retrieval and display by
  controlling homographs (words that are spelled
  the same but have different meanings)
• General Purposes
• Assist users by conveying meaning, orientation,
  and structure in a subject area
• Assist users by providing rich relationships
  among concepts and terms

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Buckland

• Proposes five different vocabularies in any
  system
• Authors
• Indexers
• Syndetic structure
• Searchers
• Formulated queries
• Formal tradition vs. document tradition

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Types of Controlled Vocabularies
Zeng, M.L. (2005). Construction of controlled
vocabularies A primer.

• Subject Heading List
• Taxonomy
• Thesauri
• Classification Scheme
• More terminology on Leonard Wills site
• http//www.willpowerinfo.co.uk/glossary.htm

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Subject Heading Lists

• General list of terms (words and phrases), not
  limited by discipline or subject area
• Terms are called subject headings
• The distinction between thesauri subject
  heading lists is largely historical (subject
  heading lists are older) there are very few
  subject heading lists because they are so
  expensive to maintain
• Terms are mainly subject attributes, but there
  are many exemplified attributes used in
  subdivisions
• Example Library of Congress Subject Headings
  (LCSH), used in library catalogs
• Sample terms France Colonies History
  18th century Time and space Juvenile
  fiction Frogs (notice the use of
  subdivisions, marked here by dashes thesauri
  seldom use subdivisions)

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Taxonomies

• List of terms (words and phrases) that may be
  general or subject/discipline/domain specific
• Terms are called taxons or (simply) terms
• Terms represent subjects, disciplines/domains,
  and exemplified attributes
• Used in digital environment only
• Examples Microsoft Corporation intranet
  taxonomies Yahoo taxonomy used in the Yahoo
  directory
• Sample terms from the Yahoo taxonomy (in Yahoo,
  youll find these at the top of the screen as you
  browse through the directory) Education
  Science gt Agriculture gt Research gt Government
  Agencies Health gt Nursing Health gt
  Education

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Thesauri

• Thesauri (pl.) / Thesaurus (s.)
• List of terms (words and phrases) that are
  usually limited to a specific subject or
  disciplinary area
• Terms listed in a thesaurus are often called
  descriptors
• Thesauri were mostly defined and developed after
  the advent of the computer and were created for
  use in an computerized environment (or with
  computers in mind)
• Terms are usually subject (about) attributes, but
  some thesauri also contain exemplified (example
  of) attributes- http//www.e-government.govt.nz/nz
  gls/thesauri
• Example ERIC Thesaurus (education)
• Sample terms from the ERIC Thesaurus School
  community relationship College entrance
  exams Age grade placement

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Classification Schemes

• Chart of subject categories contextualized by a
  hierarchical structure
• Terms are lists of codes (notation)
• Terms are called classes and class numbers
• Classification schemes make use of disciplinary,
  subject, and (sometimes) exemplified attributes
• Used often to arrange physical documents
  sometimes used in online environments

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Classification Example

• Examples Dewey Decimal Classification (DDC)
  Universal Decimal Classification (UDC) Colon
  Classification
• Sample entries (DDC)
• 510 (meaning Mathematics (a discipline and a
  subject))
• 512.57 (meaning Mathematics / Linear,
  multilinear, multidimensional algebras / Factor
  algebras)
• 362.582 (meaning Social problems and services
  / Problems of and services to the poor /
  Financial assistance)

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Four Types of Classification

• Kwasnik describes four classification systems
• Hierarchies
• Trees
• Paradigms
• Facets
• Paradigms are useful primarily for analysis of
  subject gaps and relationships in a constrained
  space
• Trees are a poor form of hierarchy with limited
  relationships
• Well look at the other two in some detail over
  the next two weeks

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Hierarchies

• Good for representation of knowledge in mature
  domains where the nature of the entities and
  relationships are well known
• Youll see examples of these in the thesauri that
  we will look at in todays exercise
• Require a model that describes what entities are
  included, with rules of association and
  distinction
• Tend to be monolithic and cumbersome for large
  domains

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Facets

• Actually a different approach rather than a
  different structure
• May use hierarchies or trees as part of the
  structure
• Originated in the work of S.R. Ranganathan
• Proposed that any object could be viewed in five
  ways personality, matter, energy, space and
  time (PMEST)
• Being used more and more in modern information
  systems because of flexibility in meeting
  multiple needs

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Collaborative Tagging

• Points out issues of basic level and
  collective sensemaking
• Tug of war between personal storage
• Identifying qualities
• Self reference
• Task organizing
• and public nature of access
• What or who it is about
• What it is
• Who owns it
• Categories
• Stability emerges from imitation and shared
  experience

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Trees vs. Tags

• Weinbergers article postulates three types of
  vocabularies
• Trees (hierarchies)
• Facets
• Tags
• Golder/Huberman and Weinberger both point out
  that each approach can be useful in particular
  situations
• Choosing your approach is part of the process of
  subject and domain analysis

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Steps in Constructing CVs

• Define your domain
• Gather concepts
• From user interviews, search logs, content
  analysis, preexisting vocabularies
• Select your approach
• Extract terminology
• Control your terms
• Organize your terms
• Maintain, maintain, maintain

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Questions?

• If not, take a break!!!

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Exercise 6a

• Purpose is to explore some existing controlled
  vocabularies to investigate their differences and
  similarities, how useful they might be for
  subject access, and to become familiar with the
  structure of controlled vocabularies in general
• Spend the next 45 minutes on Exercise 6a
• Ask questions and talk!!!
• Be sure to hand in completed work at the end of
  class for credit!!!

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Thursday

• Well start to look at ways to build controlled
  vocabularies and the rules associated with them
• Remember to read assignments BEFORE class