Controlling values

The equivalence relationship

The vocabulary problem

What is this?

Synonymy

Restroom, bathroom, toilet, loo, facilities, WC, ladies’ room, mens’ room, little girls’ room, little boys’ room. . .

Synonymy: Using different words to identify the same concept.

Another vocabulary problem

What is mercury?

What is bank?

What is python?

What is java?

Polysemy

Polysemy: Using the same word (morphologically speaking) to identify different concepts.

Java: Island in Indonesia, specific variety of coffee bean, generic term for coffee, object-oriented programming language.

Yet more vocabulary problems

The White House has been lobbying Congress to support the proposed budget. . .

Freedom of the press is an important value in the United States. . .

I’m tired of taking the bus; I need some new wheels. . .

Metonymy and synecdoche

Metonymy: Using a related concept to stand for another concept.

Synecdoche: Using the word for part of something to stand for the entire thing.

Furnas, et al’s experiment

Furnas, et al asked people (including subject experts) to label a variety of items (recipes, text editing operations, “common content objects”). Surprise, there was little agreement among the names submitted by participants.

Conclusion: “The idea of an ‘obvious,’ ‘self-evident,’ or ‘natural’ term is a myth! Since even the best possible name is not very useful, it follows that there can exist no rules, guidelines or procedures for choosing a good name, in the sense of ‘accessible to the unfamiliar user.’

Furnas, et al’s recommendations

Furnas, et al suggest that interface designers:

• Implement unlimited aliasing.

• Disambiguate terms that can be used in multiple senses by presenting possibilities to users and asking them to select the appropriate one.

Limitations of Furnas’s study

• Participants were asked to label objects, not how they would search for objects.

• The study assumes a search interface, not a browsing (or menu-driven) interface.

In a search interface, users must recall or guess an object’s name. In a browsing interface, users merely need to recognize the appropriate term.

Vocabulary problems and information systems

Designers of organizational systems have been grappling with the ambiguities of language for many years.

Synonymy, polysemy, and so on complicate the goal to collocate, or bring together, like items in an information system (those by the same author, with the same title, or on the same subject).

Vocabulary control

In LIS, vocabulary control is similar to Furnas’s idea of aliasing: multiple terms that might stand for the same concept are grouped together.

One term is typically designated as preferred: this is the term used in a display (or, in a card catalog, the card with the preferred term would actually have the entry; the other terms would just be cross-references).

Example of a controlled term

Preferred term: bathroom

Equivalent terms: restroom, loo, toilet, WC, ladies’ room, mens’ room, little girls’ room, little boys’ room, ladies room, ladys room, lady’s room, ladie’s room, ladys’ room...

Digression into the library catalog

Library catalogs have three traditional access points: author, title, and subject. In the old card catalog, these were the three ways that users could search.

Each of these access points has associated vocabulary control.

Catalog entries

Entry is an old term for a catalog record. For example, Herman Melville’s Moby Dick might have an entry in the card catalog under the subject Fiction—Whaling.

The main entry designates the primary access point and, in the card catalog, the card with all the bibliographic information. (Other entries might have a cross-reference to the main entry only.)

The entry for Moby Dick under Fiction—Whaling might say merely “See Melville, Herman. Moby Dick.”

Main entry confusion

For many people, the designation of a primary access point or main entry is anachronistic in the world of online systems. We can search any attribute now: why select a “primary” one?

Taylor notes three arguments for retaining the main entry: standardization of citation, subarrangement, and collocation of works.

Control of names

Names, such as author or title names, are controlled via authority files.

Authority files both disambiguate names that identify multiple people or items and group variations for the same person or item (that is, they deal with polysemy and synonymy).

Authority file examples

In the UT author authority file: headings for Patricia Williams:

• Names are disambiguated by using middle initials and dates of birth.

• Cross references are used for some authors.

• There may still be two headings for one person!

Digression 2: Power catalog searching

To increase the precision in library catalog searches, avoid keyword searching.

Instead, search the appropriate authority file first, then search using the preferred heading. Magic!

Searching the authority file typically necessitates proper query formation (e.g., last name, first name for author searches).

Digression 3: Pseudonyms in the catalog

Pseudonymous identities are maintained in AACR2 (in older catalogs, everything went under the author’s real name).

For example, “Carolyn Keene,” the name used by multiple people as the author for the Nancy Drew novels, is maintained as an author entity in the authority file.

Controlled subject vocabularies

Subject vocabularies have varying amounts of structure (e.g., relationships between terms).

Thesauri may include equivalence, hierarchical, and associative relationships. Thesauri can also be faceted (that is, represent multiple aspects of a subject...we will discuss facets in depth later in the course).

Example thesaurus entry

Dark chocolateBT ChocolateRT Single-origin chocolateUF Semisweet chocolate

Baker’s chocolateSweet chocolate

SN Chocolate without milk solids and with less than 70 percent chocolate mass.

BT: broader term, one level up in a hierarchy

RT: related term, in another facet or hierarchical branch

UF: Use for; synonyms, or non-preferred terms

SN: Scope note; definitions or usage guidelines

Equivalence in thesauri

Similar concepts may be treated as equivalents as judged appropriate by the thesaurus designer.

Examples:

BeerUF ale, porter, stout, pilsner, bock, IPA. . .

CartographyUF maps

Disambiguation in thesauri

Polysemous terms are often identified by adding qualifying terms in parentheses.

Mercury (element)

Mercury (god in Greek mythology)

Search engines may use ask users to select the sense they want.

Using controlled vocabularies: MeSH and PubMed

The Medical Subject Headings (MeSH) index journal articles for the PubMed database.

Keyword searches in PubMed are automatically expanded with MeSH. Searches can also be explicitly limited to MeSH terms, which can increase precision.

The comparison to a system like Google Scholar is illuminating.

Standards for controlled vocabularies

There are a number of standards for thesaurus construction: ISO, NISO, British.

These can be quite detailed, but they provide mostly syntactic guidance: e.g., terms should take noun form.

Summary

• Controlled vocabularies increase precision and recall in searching by identifying equivalent terms.

• Authority files are types of controlled vocabularies that describe preferred forms of author names and names of works.

• Thesauri are subject-based controlled vocabularies that include hierarchical and associative relationships in addition to equivalence relationships. Thesauri can also be used as browsing interfaces.