module 9a: classification schemes imt530: organization of information resources winter, 2007 michael...

Module 9a: Classification Schemes

IMT530: Organization of Information Resources

Winter, 2007

Michael Crandall

IMT530- Organization of Information Resources 2

Recap

• Hierarchical and faceted approaches are not mutually exclusive– You can use hierarchies under facets to help with

entry vocabulary and cross references

• You may not always be able to apply mutual exclusion and exhaustivity to facets, but you should use these principles to help clarify – Spiteri’s Idea Plane is where you do this work– Try to apply terms from all facets to each object

(webpage) you’re tagging to see what happens– If it doesn’t make sense, you probably need to

rethink your facets


Module 9a Outline

• What is a classification system?

• Types of classifications

• Characteristics of classifications

• Taxonomies

• Classification vs. categorization

• Purposes of classification


What Makes a Classification?

• A verbal description of concepts represented in the scheme

• An arrangement of these descriptions in a classed or logical order for users (schedules)

• A notation that shows the logical order• References to guide users to related aspects

in the scheme• An alphabetical index that leads to the

notations• Instructions for use• A maintenance organization


Two Types of Classification Systems

• Classed – e.g., classification schemes such as Dewey Decimal Classification (DDC)

• Alphabetico-classed – e.g., taxonomies such as Yahoo’s categories

• Both share common characteristics:– Classes- the smallest component of a subject

hierarchy (each node is a class, composed of subclasses)

– Arrays- comprised of all “sister” classes that have the same “mother”; e.g., “roller chairs” and “straight back chairs” comprise one array, etc.

– Chains- a string of classes that move up and down a hierarchy (breadcrumb trail on the web)


Classed Systems: Definition

• Classed systems use notation as terms• Notation frequently includes combinations of

numbers, letters, and punctuation• Notations always have a meaning, which is

frequently not understandable by just looking at the notation itself (i.e., the DDC number 517 has a meaning)

• Notation may be expressive or hospitable• The Library of Congress Classification (LCC)

is an example of a classed system


Classification Example: DDC


Alphabetico-Classed Systems: Definition

• Alphabetico-classed systems are classifications that use words as terms instead of notation

• Like classed systems, hierarchical structure and meaning are inherent in each term

• Because words are used in terms, the terms are usually understandable without interpretation by an expert


Alphabetico-classed Systems

• An example of current alphabetico-classed systems are web-based taxonomies

• However, alphabetico-classed systems have a long history of use in knowledge organization in encyclopedias and library catalogs

• They did not work well in most manual environments because subjects often got buried very quickly and were difficult to find if you didn’t know the hierarchy in which they were embedded


Contrasting Alphabetico-classed and Classed Terms

• Sample alphabetico-classed term for papier mâché: – Arts and Humanities > Visual Arts >

Sculpture > Papier Maché• Sample DDC classification number

(term) for paper mache:– 745.542 (its meaning, or hierarchy, in

Dewey, is: Arts > Drawing and Decorative Arts > Decorative Arts > Handicrafts > In papers > Papier-mâché)


Classifications are Pre-Coordinated

• Notice that in both of the papier mache examples, both of the terms carry the meaning of an entire hierarchy

• Because of this, all classifications are pre-coordinated – almost all terms contain multiple concepts in that they carry with them the concepts inherent in an entire subject hierarchy


Classification in Libraries

• Driven by need to arrange materials and provide systematic access

• Traugott Koch’s types of classification schemes reflect this– Universal schemes- DDC, UDC, LCC– National schemes– Subject specific schemes- NLM, EI

• Issues discussed in Taylor relate to this function of classification


Snoopy

• Bertolucci points out the need to move beyond the general classification schemes used in libraries for most local applications– Points out different drivers and different user

populations– Usually constrained by narrower needs– Often are built for temporary use

• These smaller classification structures are often lumped under the term “taxonomies”

• Most likely to be the model you will encounter


Yahoo Taxonomy

• Yahoo Directory is a large taxonomy- http://dir.yahoo.com

• Although each term in the taxonomy stands for a particular subject or class (e.g., “Disabled pets”), the term itself carries the meaning or context of the entire domain in which it is situated (“Science > Biology > Zoology > Animals, Insects, and Pets > Pets > Disabled Pets”)

• Cross-references to related classes out of the current sequence are indicated by the @ symbol (similar to a “see also” reference in a CV)

• In web taxonomies, you can either browse to an term embedded in a hierarchy (e.g., disabled pets), or search on it to retrieve it immediately

http://dir.yahoo.com/


Classification vs. Categorization

• Classification is different from categorization• Categorization is grouping based on common

characteristics (ordering and establishing hierarchical relationships is not necessarily involved)

• Categorization is used often in the information professions – pamphlet files, vertical files, and websites

• If there are very few files and all are visible, there is usually not a particular need for ordering or hierarchical structuring


Sample categorization – the “Idea Index”


Ways of Building Classifications

• Bottom-up– Classes are developed empirically, through

observation of cases (sometimes called taxonomy; in LIS, bottom-up systems are often a result of literary warrant policies)

• Top-down– Classes are developed conceptually;

observation of cases is not involved (sometimes called typology)


Purposes of Classification Systems

• To group topics or physical items on the same subject together (collocation) to promote browsing

– Classification by discipline or domain makes possible browsing in the context of a discipline or domain

– Browsing helps us to become aware of items that we did not previously know about

• To fix a topic or item at a particular location and context in the universe of knowledge

– All items are placed in context with all other items – each item has a location which may be contrasted or compared to the location of every other item


Purposes of Classification Systems

• Placing of an item in a classification gives us rich information about that item and its context

– James Welch, Fool’s Crow (assigned the LCC class number PS 3573.E44)

– PS3573.E44 = American Literature, 1960-, “W” authors, James Welch

– In a taxonomy, Welch’s novel might be placed in this kind of context: American literature > 20th century > Northwest fiction

– In a physical arrangement, a person can learn something about Fool’s Crow by what other items it resides next to


More Purposes of Classification

• To provide a location device based on subject content for individual items that will help user locate a particular item

– In libraries, classification numbers are used for storing physical documents, and for returning them to their place when they’ve been removed

– In taxonomies, you can guide users to similar content through breadcrumb trails


Questions?


Exercise 9a

• Spend the next 45 minutes exploring the examples in Exercise 9a

• Ask questions and talk!!!

• Be sure to hand in completed work at the end of class for credit!!!

module 9a: classification schemes imt530: organization of information resources winter, 2007 michael...

Documents