Page 110 - DLIS402_INFORMATION_ANALYSIS_AND_REPACKAGING

Unit 5: Information Retrieval

Subject Search Notes

Systematic subject search requires careful planning and should be conducted on several different
sources. This search type should be chosen when the user is looking for more in-depth information.
Before selecting this method, the user should already have knowledge on the databases and search
techniques s/he intends to use and know how the material has been indexed into the database (e.g. be
familiar with the subject terms).

Self Assessment

Fill in the blanks:
1. The choice of ............. depends on the information need.
2. ................. is a fast way to learn how to use a database and the way it functions.
3. Systematic ................ requires careful planning and should be conducted on several different
sources.

5.3 Search Techniques

Command Search

When constructing a command search, the keywords that are included in the search string are natural
language words that describe the topic of the search, as opposed to subject headings and thesaurus
terms. It is advisable to include several different terms that describe the same concept into the search
string; this can be done by adding synonyms, related terms and words in other languages to the
string as well. Command search is the best way to start the first stage of a systematic information
retrieval process. It is also useful when seeking information on relatively new research fields that do
not yet have established terminology or if the key concepts of the topic are very specific. After
conducting a command search, the result list may contain references to relevant documents; these
can be used when continuing the information-retrieval process by selecting essential subject terms
from the list of subject terms used in indexing the documents.
Truncation can be used in order to find all the inflected forms of keywords as well. The truncation
mark can be different in different databases, e.g. * (an asterisk) or ? (a question mark). When using
truncation, the results of the search will contain all of the documents that contain any word that
begins with the sequence that precedes the truncation mark, for example the keyword school* can
be used to retrieve documents that contain any of the following terms: school, schools, schooling.

Subject Search

The search can also be conducted by using thesaurus terms or other kinds of subject headings that
are often readily available in databases. Using controlled vocabularies, such as thesauri, usually
guarantees better search results than a command search. Subject search is conducted on the subject
heading field, i.e. the terms that were used in describing the contents of the documents contained in
the database; subject search cannot be conducted on any other field, e.g. the title. If the user wants to
expand the search to the whole reference information or full-text documents, s/he should conduct
a command search instead.

Boolean Operators

Boolean operators (AND, OR, NOT) are used when linking concepts or keywords together. The AND
operator is used when both of the keywords or concepts that the operator links together have to be
present. Using the AND operator reduces the number of results and narrows the search. For example:
teenagers AND computer games.

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