Search Strategy - II Dr. V. V. Subrahmanyam Associate Professor, - - PowerPoint PPT Presentation

Search Strategy - II

• Dr. V. V. Subrahmanyam

Associate Professor, SOCIS, IGNOU

Mismatch Between Information Need and Search Results

• Problems of online searching identified by

Fenichel’s study (1980-81) are:

– Approaches to searching vary from user to user – Major problems are with the search strategy and not with the mechanics of the retrieval system – Most of the users do not make full use of online interactive facilities – Lack of skills, charging policy, search environment and nature of question

Major causes for deviation

(Guinchat and Menou, 1990, p.314)

• Information need as perceived by end-user
• Information need as expressed in end-user’s

query

• Information need as interpreted by

Information Specialist

• Query formulation in the language of the

system

• Formulation of search expression and strategy

Contd…

• Search and retrieval operations
• Intermediate results
• Final results

Major Approaches in Searching

(Markey and Atherton, 1981; Harter, 1986, Hartley 1990)

• Briefsearch
• Block-building method
• Successive fractions method
• Citation Pearl Growing method
• Starting a search with the most discriminating

facet first

Contd…

• Starting the search with the lowest posted or

the most specific term as measured against the file

• A combination of two or more of the above

methods which is useful in actual practice of searching.

Briefsearch

• It is a quick and relatively less expensive way
• f getting a rough idea about what a database

holds about a subject.

• With the help of many more additional terms

derived from the first briefsearch further search steps can be proceeded.

• One may not adopt this technique for a full

fledged search.

Building Block Method

• Reduce a request into a series of sub-

problems.

• This strategy is logical in construction of

search mechanism but takes time in keying-in and requires knowledge of the appropriate vocabulary.

Example

• Software packages for information retrieval

– S1 software OR packages OR software packages – S2 information retrieval – S3 S1 AND S2 *OR and then AND

Successive Fractions Strategy

• This approach is a way of reducing a large set

created using AND or NOT

• Example:
• Swimming and physical fitness of women

– S1 swimming AND (wom?n OR female?) – S2 S1 AND fit? – S3 S2 AND year >= 1995

Citation Pearl Growing Method

• It begins with a very small initial set, even a

single term known to be relevant to the query.

• The resultant retrieval provides additional

relevant terms.

• These can be used to carry out further

searches on the subject.

Precision Devices

• Precision devices are used to restrict the no.
• f records retrieved.
• Such devices enable the coordination of

linking information at various stages of document indexing, search, and retrieval processes.

Recall devices

• Recall devices are used to increase the no. of

relevant references retrieved by a search expression.

• The devices includes synonym control,

hierarchical term linkage, associative term linkage, control of work forms, summation of document sets and bibliographic coupling.