1. MeSH & Principles of Classification
April 13, 2005

2. Medical Subject Headings (MeSH)
Thesaurus developed in the 1960s for online use
More detailed than LCSH for medical terminology
Pre-coordinated but not to same extent as LCSH

3. Vocabulary
Same vocabulary is used for cataloging books and for indexing journals
19,000 main subject headings
82 topical subheadings or qualifiers
Each subject heading and qualifier has a scope note and the categories under which it may be used

4. Vocabulary (cont.)
Does not include form, geographic or language subheadings
Does use publication types as headings
Kinds of study, types of study, and sources of support are specified (“check tags”)
Can limit searching by language, type, medium, location, etc.

5. Descriptors for: Cutaneous adverse events in renal transplant recipients receiving sirolimus-based therapy (journal article)
Adult
Aged
Cross-sectional studies
Edema/etiology
Female
Hair/pathology
Humans
Immunosuppressive agents/*adverse effects
*Kidney transplantation
Male
Middle aged
Mucous membrane/pathology
Nails/pathology
Sebaceous glands/pathology
Sirolimus/*adverse effects
Skin diseases/*chemically induced
Skin diseases, Infectious/etiology
Descriptors in PubMed are given in alphabetical order.
The ones with stars are the main subject headings: immunosuppressive agents-adverse effects; kidney transplantation, sirolimus-adverse effects, skin diseases – chemically induced
Some of the terms are for the subjects of the study: adult, male, aged, female, humans, middle aged – because sex and age are important factors in diseases
Some are the type of study: cross-sectional studies
Some are the organs affected: hair, mucous membrane, nails, sebaceous glands – all with subdivision pathology
Some are for the category of disease: skin diseases – with two subdivisions
On average, subject headings are applied, 3-4 being major descriptors.
Subject labels are designed to describe elements and concepts in the document rather than the whole document

6. Syntax Some subject headings are inverted
Subject headings may be subdivided, but no more than two elements are permitted
If more than one qualifier is needed, then the subject heading is repeated. Example:
Coronary disease / ep [Epidemiology]
Coronary disease / me [Metabolism]
*Coronary disease / pc [Prevention & Control]

7. MeSH Thesaurus Available in three forms online and/or in print: PubMed
Tree structure
Alphabetic list
Annotated Alphabetic List
PubMed
Demo of Tree Structure: 15 categories (alphabetic), each with subcategories (numerical)
Subcategories are in alphabetical order. Show the level of information contained in a specific display, as in the entry for Aedes

8. Alphabetic List 1st section:
every subject heading and subdivision in one alphabetical list regardless of hierarchy
notational equivalent(s)
History of the term, including year of adoption, earlier terms
Cross-references

9. Alphabetic List (cont.)
2nd section:
Categories and subcategories
Records subcategories in alphabetical order with their notations

10. Annotated Alphabetic List
Only in print form
Designed for catalogers, indexers, and online searchers
Contains scope notes, check tags, and other information not included in the Alphabetic List

11. Principles of Classification
Definitions
Uses of classification
Components of classification systems
“Characteristic of division”
Enumerative vs. synthetic schemes

12. Definitions
Classification: The systematic arrangement of objects or concepts in groups or classes according to their similarities and differences or their relation to a set of criteria. (Olson & Boll, 2001)
In bibliographic classification, like subjects are grouped together and related subjects are near one another

13. Definitions (cont.)
Class numbers or classification numbers -- symbols used to identify classes (preferably called notation since they can be alphabetic or alphanumeric)

14. Classification scheme characteristics
Dynamic
Book numbers (a.k.a. Cutter numbers) allow for subarrangement of books within a class
Principles of subarrangement within classes achieved with shelflisting
Dynamic – require maintenance; new information results in revisions of schemes, or new ways of considering information requires rethinking the organization of it
Shelflisting on May 4

15. Uses of Classification
Arrangement of materials on shelves
Arrangement of document surrogates in paper catalogs
Online manipulation of document surrogates (online shelf list) for online browsing

16. Importance of Browsing
Ranganathan’s principle: Save the time of the user
In open stack libraries, browsing is a significant method of resource discovery
In OPACs which include remote resources, the ability of users to browse an online shelflist increases the likelihood of discovering those remote resources. There is no other way at present to browse remote resources.
The library’s efforts to fully classify a collection results in time savings for users and staff.
See Thomas Mann’s book: Library Research Models: A Guide to Classification, Cataloging, and Computers.

17. Components of a Classification Scheme
verbal description of things and concepts
arrangement into a classed/logical order that is meaningful and convenient
notation alongside each verbal description; together these form schedules
references to guide user to other aspects of topics or related topics

18. Components of a Classification Scheme (cont.)
alphabetical index of terms used in the schedules with synonyms
instructions for use
mechanisms for revision

19. Characteristic of division
Groups of abstract concepts, objects, or activities are divided into smaller groups
The criterion for division is called the “characteristic of division”

20. Types of Characteristics of Division (cont.)
Genus to species (or group to member)
Primates to Apes
Whole to parts
Nervous system to Spinal cord
Continuous process
Textiles, Carding, Spinning, Weaving, Finishing

21. Types of Characteristics of Division (cont.)
Increasing complexity
Music for duets, for trios, for quartets
Chronological (history of a country)
Czechoslovakia, , ,
Spatial: Continent to Country
Europe to Czech Republic
Other types of characteristics are possible

22. Characteristics of Division (cont.)
Division continues until no other divisions can be made
Creates a hierarchy
Overlapping hierarchies may exist as there may be more than one way of dividing a topic

23. Enumerative Classification Schemes
Every topic that can be classified is enumerated in the scheme
Topics not enumerated separately must be classed with a broader topic
Narrow compound topics can be accomodated by narrowing the class
LCCS and DDC

24. Linearity
Linearity: documents can only be shelved by one characteristic
Only major aspects of a work are considered in classification
Compound topics present a problem

25. Solutions to compound topics
Rules:
Classify by emphasis of the work
Classify by one criterion when two apply
Classify by the first class in the schedules
These rules can be arbitrary and are of no use to browsers

26. Synthetic Classification
Combine notations for different concepts to create compound notations
Faceted classification is one type of synthetic classification
Ranganathan’s colon classification – five facets
Read more about it in Chapter 7, SAOC!