Post coordinate indexing .. Library and information science

Harsha. E.C
CUANLIS 008
University of Calicut

 Post Coordinate Indexing
 Features
 Types( Uniterm, Peek a-boo)
 Advantage , Disadvantage
 Conclusion

 Post coordinated indexing is the opposite of
precoordinated indexing
 The searcher controls how terms are combined
for a search and the set of document retrieved
 This will general increase recall but usually
decrease precision
 Allows searchers the freedom to freely combine
many terms that are relevant to the search

 No fixed sequence order or citation order is necessary
 Every term get equal weight
 Co-ordinate of concept is done by the searcher at the
search stage
 The searcher has the complete freedom to coordinate
the index terms
 Multidimensionality in relationship of concept can be
retained
 There is usually a large number of entries in post co-
ordinate indexing system than the precordinate
indexing system

 Searching a uniterm file is difficult because it relies on the
ability of the searcher to notice matching numbers on the
card that are received in response to a given query.
 This process is based on simple process: Each card is divided
in to small unit of numbered squares , each unit bearing a
specific number, and a document number is punched on the
apt position on the card. Thus a document number in which
the term , written on the top of the card , appears at the
time of searching. The card are then placed in a box against
a source of light . Light will pass through those card that
have punches at the same position .The numbers represented
by these position will contain all the terms present in the
query , and thus will be the output.

A peek a- boo card contains space at the top of the
heading for posting of a term /phrase , like a uniterm
card , and the body of the card is divided uniterm card
is divided up into numbered squares ranging from 500 to
1000 or up to 10,000
A mechanism that uses optical coincidence or peek a
–boo card was devised to overcome the problem of
manual searching .This system removed some of the
problems involved in searching uniterm cards, but if
there were a large number of punches on a card , it
could easily become mutilated after being used a
number of times

 Uniterm is a combination of two words, Unit&
Term
 Unit stand for a single concept , therefore single
word representing single concept
 It was developed by Mortimer Taube in 1953 as a
technique for having bibliographical control on
research reports of scientific project in the
collection of the U S Armed Service Information
Agency
 Understood the analysis of compound word in to
the conceptual units.

 ‘’Fruit box’’ in to uniterms ‘’ fruit’’ and ‘’
box’’
 Readymade subject heading are not provided
by the indexer
 Various components of a subject are
coordinated at the output stage depending
on the query of the user
 In pre coordinate indexing, indexer pre-deter
by coordinate the mines the search
methodology subject component at input
stage

 The subject content of the document is analysed
first and their individual concept are isolated
 The concept are transmitted in to index terms
 The indexing language consist of uniterm , thus
the index is known as uniterm index
 The record of the index terms is generally
maintained in the card form
 Each card is assigned a serial no; If may be a
special no. Which is identification number of the
document
 Each card is divided in to 10 columns from 0 to 9

 The identification serial no is posted on the
term card
 The terminal digit of a number determines the
column of it’s posting
 The card will have some space at the top unique
index terms are written
 The term card are arranged alphabetically in the
tray just like catalogue card
 When searching a particular subject term , the
user have to check specific cards from the
alphabetical arrangements . Then no posted on
the column are compared to find the common
accession no, the required subject and
documents are short from the document profile

 Reduce the user’s effort of learning any
formalisms, including rules governing citation
order , to construct queries
 Single words may be combined , which increases
recall

 Sequencing is a problem if the user is unable to
make proper sequencing then he will be
misguided to anywhere and can’t find the
document
 It is very time consuming for both library staff
and user

 Flexibility
 Facilitate automatic indexing
 Easy to maintain
 Allows infinite combination
 Amenable to search mechanism outside of
OPAC’s

 False coordination result in low precision
 Lack of context in heading often hampers the
searcher’s ability to evaluate the relevancy and
usefulness of the retrieved items

Post coordinate indexing .. Library and information science

Post coordinate indexing .. Library and information science

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Post coordinate indexing .. Library and information science