Brief origins of the organization of information• Large amounts of information became

difficult to store and retrieve.• Although the classes used vary wildly

across cultures, grouping based on the class level is nearly universal.

• Organizational structures provide the context in which humans transform information into knowledge.

• It’s not just handy, it’s essential.

Humans classify “with a pronouncedly mental scalpel that helps us carve discrete mental slices out of reality” because “reality is not made up of insular chunks unambiguously separated from one another by sharp divides, but, rather, of vague, blurred-edge essences that often spill over into one another.”

-Eviatar Zerubavel (1991)from The fine line: Making distinctions in everyday life

“Cognitive scientists have noticed that much of our mental commerce with an environment deals with classes of things rather than with unique events and objects.”

-Mark Stefik (1995) from Introduction to knowledge systems

For example, the people seen below could probably all be placed in both the class “Cognitive Scientists” and the class “Nerds”. Can you think of other possible classes? Possible relationships? Clinical vs. academic cognitive scientists? Beards and nerds?

Why consider classification and taxonomy together? Both are methods for grouping objects or

ideas sharing useful, although sometimes superficial, similarities

Both group to make retrieval easier Both are very basic and pervasive

elements of information architecture It is often difficult to tell them apart It is often unnecessary to tell them apart

Why tell them apart then? To become knowledgeable about the

different limitations and possibilities in their interaction

Differential demand on and payoff for users

It is important to understand the specific qualities by which each can achieve organizational objectives

Specific qualities presented as keywords and key-dichotomies Organization Retrieval Controlled

vocabulary/thesauri Ambiguous vs. Exact Searching vs.

Browsing

Content-based vs. User-based

Descriptive vs. Navigational

Precision vs. Recall Structures vs.

Applications Concise vs. Broad

Classifications, Taxonomies, and Classifications, Taxonomies, and Ontologies -Ontologies - ClassificationsClassifications Relationships expressed are not essential, but

are based on arbitrary, external attributes (color, genre, format, geography, subject, alphabetical order)

Created broadly from the top-down, based on conceptual frameworks

Created by subject experts Usually don’t change significantly after their

creation Generally applicable to specific domains

Classifications, Taxonomies, and Classifications, Taxonomies, and Ontologies -Ontologies - TaxonomiesTaxonomies

Relationships expressed are usually essential, based on internal properties of the related pieces of information

Created concisely from the bottom-up from actual content

Created by multidisciplinary teams Are process-oriented, and so are updated frequently Oftentimes can be used and reused in different

situations and environments Relationships commonly represented hierarchically Can be include many classifications connected together

Example of internal properties of taxonomic relationship All zippers are clothes fasteners Not all clothes fasteners are

zippers Because of the essential nature

of their relationship, zippers is a sub-class of clothes fasteners, and clothes fasteners is a superordinate class of zippers

Taxonomic Hieracrhy

Clothes Fasteners

Belts Zippers Buttons

Classifications, Taxonomies, and Classifications, Taxonomies, and Ontologies -Ontologies - OntologiesOntologies Like taxonomies, relationships

expressed are also essential Scope is more overarching due to

inclusion of supplemental information • Descriptions and definitions of concepts and

their corresponding relationships Can include many sub-class taxonomies Can include many sub-class taxonomies

connected togetherconnected together

Classifications, Taxonomies, and Classifications, Taxonomies, and OntologiesOntologies Classifications guide users to a body of

information Taxonomies guide users through a body

of information Ontologies guide users in becoming proficient in the retrieval of and understanding of a particular body of information

Classification To classify something is to identify it as a

member of a known class On the Web, information architects

organize classification schemes into either exact or ambiguous schemes

Classification problems begin with data and identify predetermined classes as solutions

Exact classification schemes Items are categorized mutually

exclusively Useful to users who know exactly what

they are looking for By definition, are easier to create and

maintain than ambiguous schemes Alphabetical, chronological, geographical

Alphabetical schemes Directories and lists User must have a good idea of what they

are searching for and be able to spell it On the Web, usually utilized deeper in

the scheme inside of sub-sites

Chronological schemes Have an intuitive advantage for users

because they are organized in the same linear scheme in which humans experience the dimension of time

Yearbooks, historical sites, and news headline sites

Ebay offers results organized by a few different types of chronologies

Geographical schemes Have intuitive appeal to rich spatial faculties

and needs of users in their experience of reality

Geographical divisions coincide with governing bodies which restrict and encourage behaviors through law and language

Requires knowledge of geographical divisions and map reading on the part of the user

Ambiguous classification schemes Items are categorized into intellectually

meaningful groups Useful to users who don’t know quite what

information they are searching for Facilitate iterative, serendipitous learning Audience-based, Subject-based, Task-based Each should be based on scheme specific

research and development processes (e.g. user and task analyses)

Audience-based classification schemes Makes sense if the informational domain

caters to clearly delineated audiences Homepage becomes a filter that leads to

sub-sites organized some other scheme Suggests customization/personalization Recommendations are sometimes

powerful, sometimes failures

IA research for audience-based classification schemes Map services and applications to their

appropriate group Discern what types of technology-use are

associated with specific populations Find points of overlap between audience

categories User research sessions, usage statistics,

search log analysis, focus groups, critical incident reports

Subject-based classification schemes Most immediately recognized are the library

classification schemes (DDC, LC) When used in IA, they generally work best

when hybridized with other types of schemes Are challenging to implement because different

words, symbols, and idioms mean different things to different people

Breadth of subjects included should be decided early on because these parameters will affect much of the rest of the IA and content work for the Web site

IA research for subject-based classification schemes Solicit development team to write down

each content item that will be part of site IA’s perform card sorting exercise to

establish initial subject categories Take it to the user

• Further card sorting• Survey with questions about navigation

Continually refine

Task-based classification schemes Useful for action and transaction related

Web sites Rarely drive a Web site on their own, but

are typically embedded deeper as part of a hybrid scheme

Desire of businesses to remove labor costs will likely increase their ubiquity

IA research for task-based classification schemes The field of usability arose from the need

to research the success and value of tools and their applications

Traditional usability tests are a good fit Analyses of video-taped sessions,

navigation logs, heuristic reviews, surveys, critical incident reports

Taxonomies Information architects have two major types to

utilize: descriptive and navigational They contrast well and each excels for different

organizational and user needs Central ideas include creating hierarchies,

controlled vocabularies, and variant/preferred term and synonym relationships

Build on classifications by supporting applications and many different types of content, including images, email, search engines, process funnels, and site registration

Descriptive taxonomies Operate outside of a user’s immediate awareness Supplement information retrieval during keyword

searching IA’s create controlled vocabularies and synonym

rings which they use to maintain consistency across applications and departments

By analyzing emerging content and search logs, IA’s maintain currency and map alternative terminology used by searchers back to the preferred form

Controlled vocabularies in descriptive taxonomies Done by attaching tags to content with

metadata derived from controlled vocabulary usage logs

The resulting thesaurus with related and variant terms makes a descriptive taxonomy more robust

Using the controlled vocabulary to increase recall or precision A user’s search can be expanded to

increase recall by mapping the search term to its variants

Or a user’s search can be narrowed to increase precision by mapping a user’s term to the preferred term in the controlled vocabulary

More about descriptive taxonomies Created from the bottom-up Are called descriptive because they are

derived directly from the content that is being used

Data management vocabularies allow workers in disparate domains to report information using the same terminology• Makes it easier for management to mine information

from this data in the future

Navigational taxonomies Have a lot of overlap with exact and

ambiguous classification schemes In contrast to descriptive taxonomies,

navigational taxonomies command the user’s conscious awareness

Allow the user to guide the seeking process themselves by browsing instead of searching

Navigational taxonomies cont’d Created from the top-down based on

mental models of users Hierarchical structures visually imply

sequences of events and relationships• These relationships provide context similar to

words in a sentence Works best when users are unsure of

what they are seeking

Breadth vs. Depth Breadth is how many categories are contained

in each level Depth refers to how many levels are contained

in the hierarchy Too broad and shallow causes user too many

choices and not enough content Too narrow and deep causes user to click more

than they will stand for It is best to err on the side of broad and shallow

to allow for add-ons and to avoid restructuring the home page

Summary Distinction is more pronounced in theory

than in practice because both are essentially controlled vocabularies structured by logical relationships

Generally, as one moves from classifications to taxonomies to ontologies, the structures, relationships, and supplemental descriptions become more complex

Summary cont’d Since humans seem to perform all three

of these innately, it matters less what they are called than how their elements can be tailored to specific scenarios to improve retrieval of information, consistency of communication, and creation of knowledge

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