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Post coordinate indexing .. Library and information science

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harshaec
harshaec

This document discusses post-coordinate indexing and uniterm indexing. Post-coordinate indexing allows searchers to freely combine terms at search time, which can increase recall but decrease precision. Uniterm indexing involves analyzing documents into individual concepts represented as single terms. These terms are recorded on cards divided into numbered columns, and searching involves finding common numbers across cards to retrieve documents. While flexible, post-coordinate and uniterm indexing can be time-consuming and lack context.

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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

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Post coordinate indexing .. Library and information science

  • 2.  Post Coordinate Indexing  Features  Types( Uniterm, Peek a-boo)  Advantage , Disadvantage  Conclusion
  • 3.  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
  • 4.  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
  • 5.  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.
  • 6. 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
  • 7.  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.
  • 8.  ‘’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
  • 9.  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
  • 10.  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
  • 11.  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
  • 12.  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
  • 13.  Flexibility  Facilitate automatic indexing  Easy to maintain  Allows infinite combination  Amenable to search mechanism outside of OPAC’s
  • 14.  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