Taxonomies for Information


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  • Review of Basic Concepts & Approaches Essential concepts include: content metadata & metadata repositories navigation architectures search architectures portal architectures Information architectures in portals and web environments are increasingly complex, integrating technologies to deliver value to users. Seamless integration is the goal. Taxonomies are critical data structures that help us to build a sustainable foundation, to integrate efficiently and to manage the complexity. Whole information architecture is more adaptable and sustainable over time if it adheres to established standards and best practices. Whole Information Architecture is more cost effective if new technologies currently being researched or under development can be integrated without re-engineering the base. Like the content and processes they support, each component of a portal has a life cycle.
  • Taxonomies for Information

    1. 1. Taxonomies for Information & Knowledge Management Architectures Denise A. D. Bedford, Ph.D. Senior Information Officer - Information Solutions Group Corporate Information Systems The World Bank Group Special Libraries Association – DC Chapter – February 4, 2003
    2. 2. Who Needs to Understand Taxonomies? <ul><li>Anyone who has been charged with the task of organizing information, regardless of the context – Brick & Mortar, KM system, ILS, Portal, Records Management System, ……. </li></ul><ul><li>You may have been trained to work with a variety of Information Organization tools or trained in bibliographic control principles </li></ul><ul><li>It is probably the case that these tools were not presented as taxonomies – perhaps as rules, as record formats… </li></ul><ul><li>Professional literature also presents a confusing, often, simplistic view of taxonomies </li></ul><ul><ul><li>Assumes that a taxonomy is only hierarchical </li></ul></ul><ul><ul><li>Fails to provide a clear distinction between the structures & uses of classification schemes, subject headings, thesauri & metadata </li></ul></ul>
    3. 3. Information Management System Architectures <ul><li>The underlying architecture of a full bibliographic control system, records management system, a metadata repository or corporate information architecture is complex </li></ul><ul><li>Taxonomies are essential structures in all information management systems </li></ul><ul><li>Information managers, librarians, information architects, knowledge architects, records managers need to be able to: </li></ul><ul><ul><li>Understand the different kinds of taxonomies </li></ul></ul><ul><ul><li>Have sufficient familiarity with their purpose to select the right kind of taxonomy for an application </li></ul></ul>
    4. 4. Taxonomy Basics <ul><li>There are four types of taxonomies </li></ul><ul><ul><li>Flat </li></ul></ul><ul><ul><li>Hierarchical </li></ul></ul><ul><ul><li>Faceted </li></ul></ul><ul><ul><li>Network </li></ul></ul><ul><li>Some are explicit/visible, others are implicit/invisible </li></ul><ul><li>There are significant design consideration when implementing each different type </li></ul><ul><li>Let’s review each quickly </li></ul>
    5. 5. Definition of a Taxonomy <ul><li>“ System for naming and organizing things into groups that share similar characteristics” Jean Graef, Montague Institute </li></ul>Taxonomy Architectures Applications
    6. 6. Taxonomy Basics <ul><li>Four types of taxonomies </li></ul><ul><ul><li>Flat </li></ul></ul><ul><ul><li>Hierarchical </li></ul></ul><ul><ul><li>Faceted </li></ul></ul><ul><ul><li>Network </li></ul></ul>
    7. 7. Flat Taxonomy Structure Energy Environment Education Economics Transport Trade Labor Agriculture
    8. 8. Type 1: Flat Taxonomies <ul><li>Flat taxonomies group content into a controlled set of categories </li></ul><ul><ul><li>no inherent relationship among the categories in a flat taxonomy -- they are co-equal members of a single structure </li></ul></ul><ul><ul><li>can move from one category to another without having to think about the relationship between them </li></ul></ul><ul><ul><li>concept of a flat taxonomy may be counter intuitive to some </li></ul></ul><ul><li>Consider how often you use flat taxonomies everyday </li></ul><ul><ul><li>alphabetical listings of people in a directory of expertise </li></ul></ul><ul><ul><li>a pull-down menu of country names or geographical regions </li></ul></ul><ul><ul><li>simple alphabetical listings of product groupings </li></ul></ul>
    9. 9. Designing Flat Taxonomies <ul><li>Flat taxonomies are easy to create </li></ul><ul><li>Flat taxonomies do not require complex interface design and extensive usability testing </li></ul><ul><li>We have learned from usability engineers how to implement flat taxonomies </li></ul><ul><ul><li>Flat taxonomies used for explicit information structures generally should consist of 30 or fewer categories; </li></ul></ul><ul><ul><li>More than 30 categories may be presented in a flat taxonomy, if the categories are intuitive to users (i.e. lists of countries, states, languages, etc.); </li></ul></ul>
    10. 10. Explicit Flat Taxonomies <ul><li>’s pull down list of product categories & horizontal list of stores </li></ul><ul><li>- </li></ul><ul><li>’s alphabetical list of brand names - </li></ul><ul><li>Microsoft PowerPoint’s global functional menu & pull down menu </li></ul><ul><li>Water Resources Directory of Expertise list of keywords - </li></ul><ul><li>’s extensive picklists of reference, verse, fiction & non-fiction listings -- </li></ul><ul><li>CyberDewey’s alphabetical index to sections - </li></ul>
    11. 11. Implicit Flat Taxonomies <ul><li>Alphabetical list of water resource experts </li></ul><ul><li>Content inventories listed alphabetically by author </li></ul><ul><li>Rights management values (simple picklist) </li></ul><ul><li>Information disclosure status values (simple picklist) </li></ul><ul><li>Security classification scheme values (simple picklist) </li></ul>
    12. 12. Hierarchical Taxonomy A hierarchical taxonomy is represented as a tree data structure in a database application. The tree data structure consists of nodes and links. In an RDBMS environment, the relationships become associations. In a hierarchical taxonomy, a node can have only one parent.
    13. 13. Type 2: Hierarchical Taxonomies <ul><li>Group content into two or more levels </li></ul><ul><li>Resemble tree structures when they are fully elaborated </li></ul><ul><li>Hierarchical categories typically have only one broader or parent category. </li></ul><ul><li>Relationships among categories in hierarchical taxonomies have particular meaning </li></ul><ul><ul><li>Relationship between a top level category & subcategory may mean group membership or refinement of the top category by a particular characteristic or feature </li></ul></ul><ul><ul><li>Moving up the hierarchy means expanding or broadening the category </li></ul></ul><ul><ul><li>Moving down the hierarchy means refining or qualifying the category </li></ul></ul>
    14. 14. Explicit Hierarchical Taxonomies <ul><li>Yahoo’s Web Site Directory - organized as a subject hierarchy - </li></ul><ul><li>Internet Public Library’s two-tier collection structure - </li></ul><ul><li>Librarian’s Index to the Internet mixed hierarchy of topics and resource types - </li></ul><ul><li>Ebay’s auction categories – </li></ul><ul><li>CyberDewey’s progressive disclosure of Dewey Decimal classes - </li></ul><ul><li>Albertson’s Shop By Aisle grocery categories or Shop A to Z grocery product - </li></ul>
    15. 15. Implicit Hierarchical Taxonomies <ul><li>Electronic news story published in XML NITF format </li></ul><ul><ul><li>International Press Telecommunications Council. News Industry Text Format. Version 3.1 September, 2002. </li></ul></ul><ul><li>Classification schemes for topic areas </li></ul><ul><li>Authority control lists for abbreviations & full names (aliases) </li></ul><ul><li>Records management hierarchical fileroom structures </li></ul><ul><li>Cross source topic reference structures </li></ul>
    16. 16. Designing Hierarchical Taxonomies <ul><li>There is more than one way to implement a hierarchy: </li></ul><ul><ul><li>Progressive disclosure of layers across sites or pages -- Ebay model </li></ul></ul><ul><ul><li>Cascading or expanding menus -- United Nations web site </li></ul></ul><ul><ul><li>Pop-up menus linked to stationary menus -- United Nations web site </li></ul></ul><ul><ul><li>Category and subcategory labels in a multi-column display -- Nordstrom’s second level pages </li></ul></ul>
    17. 17. Designing Hierarchical Taxonomies <ul><li>Hierarchical taxonomies should: </li></ul><ul><ul><li>have content at every level -- empty categories present empty value to users </li></ul></ul><ul><ul><li>be less than four levels deep in most cases </li></ul></ul><ul><ul><li>be at least two categories for each branch in the taxonomy -- do not branch for a single category </li></ul></ul><ul><ul><li>be sufficient content in each category to warrant existence </li></ul></ul><ul><ul><li>balance breadth & depth -- users must work harder to use a taxonomy three categories broad & nine deep than to use one that is seven wide and two deep </li></ul></ul>
    18. 18. Hierarchical Taxonomy Design Issues <ul><li>Hierarchical taxonomies should : </li></ul><ul><ul><li>be balanced across each level of the taxonomy to provide users with a predictable experience </li></ul></ul><ul><ul><li>be offset with search functions </li></ul></ul><ul><ul><li>should never be displayed into flat structures </li></ul></ul><ul><ul><li>be reviewed periodically </li></ul></ul>
    19. 19. Facet Taxonomies Faceted taxonomy represented as a star data structure. Each node in the start structure is liked to the center focus. Any node can be linked to other nodes in other stars. Appears simple, but becomes complex quickly.
    20. 20. Type 3: Faceted Taxonomies <ul><li>Resemble flat taxonomies when implemented, but have a different structure & purpose than flat taxonomies </li></ul><ul><li>There are no inherent relationships among categories in a faceted taxonomy – like a flat taxonomy </li></ul><ul><li>Resemble a star structure -- all facets pertain to the center object </li></ul><ul><li>All categories in a faceted taxonomy relate to a single object -- may describe a property or a value, different views or aspects of a single topic </li></ul>
    21. 21. Type 3: Faceted Taxonomies <ul><li>An object may be: </li></ul><ul><ul><li>electronic book -- each facet describes some aspect of the book - the author, the title, date of publication </li></ul></ul><ul><ul><li>facets describe the country’s population, geography, economic system, political system, history, … </li></ul></ul><ul><li>Each facet may relate to facets in other taxonomies -- a faceted taxonomy describing a book may also have a link to a faceted taxonomy that describes a country </li></ul>
    22. 22. Metadata as Faceted Taxonomy <ul><li>The primary implicit application of faceted taxonomies today & historically is as implicit metadata records </li></ul><ul><li>Traditionally, libraries have been the prime users or metadata </li></ul><ul><li>Today, portals and e-business systems are primary metadata users </li></ul><ul><li>Types of taxonomies that rely on metadata today: </li></ul><ul><ul><li>IBM’s product & service catalog on the web </li></ul></ul><ul><ul><li>User interest profiles </li></ul></ul><ul><ul><li>Knowledge ‘push’ or syndication profiles </li></ul></ul><ul><ul><li>Selective dissemination of information or “push” profiles </li></ul></ul>
    23. 23. Standards Based Metadata Schemes <ul><li>Dublin Core Metadata Element - </li></ul><ul><li>GILS - Government Information Locator System - </li></ul><ul><li>VERS - Victorian Electronic Records Strategy -- </li></ul><ul><li>MARC - Machine Readable Cataloging - </li></ul><ul><li>UDDI - Universal Description, Discovery & Integration of Business – </li></ul><ul><li>TEI -- Text Encoding Initiative - </li></ul><ul><li>ISAD(G) - International Standard Archival Description - </li></ul>
    24. 24. Commercial Metadata Schemes <ul><li>Ebay’s auction item descriptions - </li></ul><ul><li>’s product descriptions - </li></ul><ul><li>Albertson’s product descriptions - </li></ul><ul><li>Nordstrom’s product descriptions - </li></ul>
    25. 25. Designing Faceted Taxonomies <ul><li>Most important design issue for faceted taxonomy is that it be suited to its purpose -- that it contain the facets that are needed, & that their behavior is clear </li></ul><ul><li>Characteristics of each facet should be defined fully and distinctly -- while all facets pertain to a common object, each has a distinct behavior </li></ul><ul><li>Users should be able to manipulate facets distinctly -- it is important to define each facet exclusively, without overlap with other facets </li></ul><ul><li>Most faceted taxonomies are implicit structures - when they are made explicit, they are generally presented as record or table formats </li></ul>
    26. 26. Network Taxonomies A network taxonomy is a plex data structure. Each node can have more than one parent. Any item in a plex structure can be linked to any other item. In plex structures, links can be meaningful & different.
    27. 27. Type 4: Network Taxonomies <ul><li>Organizes content into both hierarchical and associative categories </li></ul><ul><li>May look like a computer network topology </li></ul><ul><li>Many relationships among categories or “nodes” </li></ul><ul><li>Relationships may have many different meanings </li></ul><ul><li>Category may have more than one higher level category </li></ul><ul><li>Any category in the taxonomy may be linked to any other category </li></ul>
    28. 28. Type 4: Network Taxonomies <ul><li>Examples of network taxonomies: </li></ul><ul><ul><li>Topic maps or ontologies </li></ul></ul><ul><ul><li>Thesauri -- !! A Thesaurus is NOT just a Hierarchy!! </li></ul></ul><ul><ul><li>Semantic networks </li></ul></ul><ul><ul><li>Implicit cross-walks for thesauri & controlled vocabularies from different knowledge domains </li></ul></ul>
    29. 29. Implicit Network Taxonomies <ul><li>Thesauri, concept maps & semantic networks can be explicit or implicit </li></ul><ul><li>Can be designed transparently into the knowledge management system as: </li></ul><ul><ul><li>thesaurus facilitated search systems </li></ul></ul><ul><ul><li>recommender engines (...if you liked this, you might also like this) </li></ul></ul><ul><ul><li>vocabulary cross-walks from one source system to another </li></ul></ul><ul><ul><li>topic map cross-walks from one knowledge domain to another </li></ul></ul>
    30. 30. Explicit Network Taxonomies <ul><li>At one end of the scale we find simple, explicit network taxonomies such as topical taxonomies with See also references, or fully exposed thesauri </li></ul><ul><li>At the other enc of the scale, we find more complex, explicit network taxonomies such as visual concept maps or visual semantic networks. Consider the following example of network taxonomies accessible on the web: </li></ul><ul><ul><li>World Bank Group’s Thesaurus – </li></ul></ul><ul><ul><li>UMLS Semantic Network - </li></ul></ul><ul><ul><li>Inxight’s Star Tree concept maps - </li></ul></ul>
    31. 31. Designing Network Taxonomies <ul><li>Structure you use to maintain the network taxonomy may not work well for display -- may have to break it into one or more types of taxonomies to implement it </li></ul><ul><li>Different kinds of relationships may be implemented in different ways - a single approach to display all types of relationships may not be effective </li></ul><ul><li>Three-dimensional presentations are well suited to network taxonomy implemented, but should be usability tested with users </li></ul><ul><li>Consider how the user will navigate a three-dimensional presentation </li></ul><ul><li>Try to maintain a consistent level of granularity of categories - avoid mixing pre-coordinated subject headings or broad classes with concepts </li></ul>
    32. 32. Conclusions <ul><li>Every Information Professional’s ‘knowledge toolkit’ should contain a basic understanding of taxonomies & their suitability to different applications </li></ul><ul><li>Taxonomies are important building blocks in a full function information architecture </li></ul><ul><li>Knowledge of taxonomies will be a skill in increasing demand as the need to organize information grows </li></ul><ul><li>Need the organize information is growing exponentially, consistent with the amount of information produced, stored & disseminated </li></ul>
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