why are taxonomies necessary?

© 2007 by ContextualAnalysis, LLC

Why Are Taxonomies Necessary?

By Fred Leise

ContextualAnalysis, LLC


Taxonomies are sets of terms (controlled vocabularies or CVs) used to tag documents or other content objects.

Taxonomies may also be used as browsing hierarchies or for search enhancement.

What Are Taxonomies?


Taxonomy terms are collected into groups called attributes. Each attribute (or facet) describes one property of your content.



Example:

Attribute: Office Location

Terms: London

New York City (NYC, Big Apple)Washington, DC


Alternate Terms


In this example, “NYC” and Big Apple” are given as variants for “New York.”

Variant terms are used to expand search queries. If a user enters “New York” the search system expands to search “New York or NYC or Big Apple.



Search query expansion ensures that more relevant information is found, even though it might use terms the searcher hasn’t thought of.



Other typical attributes include:

Author

Creation Date

Audience

Version Number

Subject



There is an international standard for metadata, the Dublin Core Metadata Element Set, consisting of 15 attributes.



Good metadata schemas (collections of attributes) will adhere as closely as possible to the Dublin Core standard.

More information is available at: www.dublincore.org



Well designed taxonomies:

1. Enable users to find relevant information quickly and efficiently (improved retrieval)

2. Lead users to additional relevant information, providing upselling and cross-selling opportunities



Well designed taxonomies:

3. Assists authors in consistently tagging content



Proper use of taxonomies results in:

Less time wasted searching for information

Fewer failed searches

Fewer abandoned interactions

Increased income

Reduced customer assistance costs



English is rich in words that mean the same or nearly the same thing

feline/cat

car/automobile

travel/journey/excursion/trip

jeans/denims/Levi's/501s

Why Are Taxonomies Important?


Result: scattering of information.

No matter what term you use in a free-text search, you get only part of the relevant information.

The rest is not retrieved because it uses different terms to describe the same concept.



Consider the example of mobile devices.

There are many ways that users can refer to them:

Personal digital assistants

Handheld computers

Blackberries

PDAs



If users don’t know the term you use to label the information they are looking for, they waste time browsing or give up their search completely.

They are victims of a communication chasm.



You use the term “cat.” I use “feline.” If we each search a recipe database that uses both terms with equal frequency, we will get back only half the appropriate recipes, a recall ratio of 50%



Solution: Add a controlled vocabulary to the search system that gives “feline” and “cat” as equivalent terms.

Search queries will be expanded appropriately.



English is rich in words that have more than one disparate meaning

Pitch

To throw a baseball

A tar-like substance

A salesman’s monologue



Bank

Where you store money

The side of a river

To carom a cue ball off a pool table rail

To prepare a fire for the night

To maneuver a plane for a turn



Result: Lots of false drops (irrelevant information), resulting in poor precision.



Solution: use a CV that includes scope notes (definitions) or that uses facets.

Example: Think about searching for the term “Rembrandt.” You might get the following results.




Rembrandt GoSearch

The painter Rembrandtwas one of the greatestof all the Dutch realists….

If you want to whitenand brighten yourteeth, there is no betterbrand than Rembrandt.



You probably are interested in only one of these “Rembrandts.” So half of your search results are irrelevant.

Now consider what happens if you were able to specify the type of object you are looking for, either an artist or a toothpaste brand.



The painter Rembrandtwas one of the greatestof all the Dutchrealists….

If you want to whitenand brighten yourteeth, there is no betterbrand than Rembrandt.

Artist

Brand Name

Rembrandt

Rembrandt



You get only results relevant to what you are interested in.

Here, having search boxes identified by attribute (faceted searching) lets you hone in quickly on the particular information you want.



You could also use one search and let users filter or narrow results after their search.


Roles for Taxonomies

Tagging documents for a content management system

Provides administrative metadata to control authoring and publishing processes

How are Taxonomies Used?



Administrative metadata: example

Document # AuthorDepartment Creation datePublication date Expiration date




Tagging document contents for a content management system

Provides metadata to support search

Ensures inter-indexer consistency




Tagging document contents for a content management system

Controls subject scattering

Increases search results relevance: tags “aboutness” not just mentions of a word




Search engine component

Translates user’s terms into those used to tag items (increases precision and recall)

Offers options for expanding or reducing scope of search using broader or narrower terms




Search engine component

Differentiates between multiple meanings of terms



Taxonomy Use: Search Results

rei.com



Operating as a browsing hierarchy

Organizes content using taxonomy terms as category labels

Represents taxonomy hierarchy by browsing levels



rei.com

Level 1

Level 4Level 3

Level 2


Synonym Ring

Identifies words with equivalent meanings (in a given context)

rock = stone

CD-ROM = CD = disk

money = dough = bucks = greenbacks = legal tender

Types of Taxonomies


Synonym Ring

When one of the words in a synonym ring is searched for, the search engine expands the search and returns items containing any of the words in the ring.

Types of Taxonomies


Authority File

Has all the features of a synonym ring, plus the identification of preferred terms (approved terms/descriptors/keywords) for tagging content.

Types of Taxonomies


Taxonomy

Also called hierarchy or classification.

All features of authority files, plus the broader term (BT) and narrower term (NT) relationships.

Types of Taxonomies


Taxonomy

All terms must be part of a hierarchical relationship (no orphan terms).

Taxonomies may be presented in hierarchical or alphabetical format.

Types of Taxonomies


total compensation . compensation . . base salary (salary) . . deferred payments (deferred compensation) . . variable pay . benefits . . 401(k) plan . . health benefits . . . dental plan . . . disability insurance

Types of Taxonomies: Taxonomy Example


Thesaurus

Plural form: thesauri

All the features of taxonomies, plus the associative relationship of related terms (RT)

Types of Taxonomies


Types of Taxonomies:Thesaurus Example, Alphabetical

Building Permits BT Permits

Business Licenses BT Licenses

Business Taxes BT Taxes

Fees RT Taxes

Licenses NT Business Licenses RT Permits

Operating Permits BT Permits

Permits NT Building Permits; Operating Permits RT Licenses

Taxes NT Business Taxes RT Fees


Types of Taxonomies:Thesaurus Example, Hierarchical

Vocabulary Terms Related Terms

Licenses, Permits & Taxes

. Fees Taxes

. Licenses Permits

. . Business Licenses

. Permits Licenses

. . Building Permits

. . Operating Permits

. Taxes Fees

. . Business Taxes


Synonym Ring

+ preferred terms

= Authority File

+ broader/narrower terms

= Taxonomy

+ related terms

= Thesaurus

Types of Taxonomies—Summary


Facets are fundamental categories by which an object or concept may be described

Example: some facets describing a toy ball:

size, weight, shape, color, texture, material

Taxonomies and Facets


Uses of Facets: Browsing Hierarchies

Facets allow users to follow the path best matching the way they think (their mental model).



Uses of Facets: Browsing Hierarchies

Example: epicurious.com > recipes > browse

Main ingredient Cuisine Preparation method Season/occasion Course/dish




epicurious.com


Uses of Facets: Fielded Search

Allows for greater specificity, thus increasing search precision.

But this is usually more complicated for users than simple searching, so it is often introduced as option on results page.



alibris.com Advanced Search


epicurious.com Advanced Search


Requirements for Browsing/Search Facets

Development of metadata schema

Development of appropriate controlled vocabularies

Proper content tagging



Aitchison, Jean. Thesaurus Construction and Use: A Practical Manual. 4th ed. Chicago: Fitzroy Dearborn Publishers

Resources


Resources

International standard for metadata: Dublin Core Metadata Element Set (ISO Standard 15836-2003)

http://www.niso.org/international/SC4/n515.pdf


National Information Standards Organization. ANSI/NISO Z39.19:1993. Guidelines for the Construction, Format and Management of Monolingual Thesauri. Bethesda, MD: NISO Press, 1994

Rosenfeld, Lou, and Peter Morville. Information Architecture for the World Wide Web: Designing Large-Scale Websites. 3d ed. O’Reilly Publishers, 2006.

Resources


Sinha, Rashmi. Beyond Cardsorting: Free-listing Methods to Explore User Categorizations

Available at: http://www. boxesandarrows.com/archives/ beyond_cardsorting_freelisting_ methods_to_explore_user_categorizations.php

Steckel, Mike, Karl Fast and Fred Leise. Creating a Controlled Vocabulary. 2002

Available at: http://www.boxesandarrows.com/archives/ creating_a_controlled_vocabulary.php

Resources


Contact Information

Fred Leise

www.contextualanalysis.com

[email protected]

@ChicagoIndexer

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