Page 205 - DLIS402_INFORMATION_ANALYSIS_AND_REPACKAGING

Information Analysis and Repackaging

Notes • Organisation into Hierarchies: Once the categories are identified, the next stage is to orga-
nize each term into hierarchies.
• Creation of Alphabetical Thesaurus: Once the hierarchies are established, the classification
is inserted to create alphabetical thesaurus. Each term becomes an entry and its hierarchical
relationships are denoted by BTand NT. Allthe BTand NTterms should reciprocate. Similarly
the non-hierarchical relationships are shown through use, used forandrelated terms (RTs).
Normally, one step up and one step down is followed.
• Presentation of Thesaurus: Each block of entries are arranged according to requirement. It
may be alphabetical, systematic (to complement) or graphic.
• Evaluation: Once the thesaurus is compiled it needs to be evaluated to assess its retrieval
effectiveness.
• Maintenance: Once a thesaurus is developed, it should be maintained properly. New terms
need to be added or deleted as the case may be. This has to be done continuously.
• Use of Computers: The collection of terms as mentioned earlier is very tedious and time
consuming. Computers can be effectively used in gathering of terms. Terms can be derived
from machine readable databases through the use of statistical techniques. Construction of
thesaurus is largely an intellectual activity as far as delineating the relationships of terms is
concerned. Once the terms are organised into facets and hierarchies, the use of computers can
be useful. The computers can print/ display. Further, computer readable thesaurus data can
be used for photocomposition to produce the print version. The most important application
of computer is in the maintenance of thesaurus. The addition and deletion of terms may be
done very effectively through the use of computers. Many thesaurus are now available in
computer readable form and linked with the databases. While searching, the system auto-
matically converts the terms into the terms of thesaurus and conducts the search.

11.6 Structure of an IR Thesaurus

A thesaurus is a reference work that lists words grouped together according to similarity of meaning
(containing synonyms and sometimes antonyms), in contrast to a dictionary, which contains definitions
and pronunciations. In Information Science, Library Science, and Information Technology, specialized
thesauri are designed for information retrieval. They are a type of controlled vocabulary, for indexing
or tagging purposes. Such a thesaurus can be used as the basis of an index for online material.

Figure 11.3

What do you call it?

Balance?
Scale?
Pair of scales?
Beam balance?
Magnifier?
Lens?
Magnifying glass?

Bicycle?
Cycle?
Push-bike?

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