Selection of online databases using switching vocabularies

Currently, hundreds of bibliographic online databases are available for searching. The novice user of an online information retrieval system must first determine which of these databases is appropriate for the information being sought. There are several directories which contain brief descriptions of the contents of various databases which may be useful for an initial determination of the major databases in the subject area of interest. One can then examine more detailed descriptions of the contents, years of coverage, and the structure of individual databases. Once the major databases have been identified, the user must then determine which of these databases contain the appropriate search terms for the information sought. The user can consult various thesauri and lists of subject headings, published by some of the database producers. For example, only approximately one third of the databases available on DIALOG have published thesauri and only about one dozen have online thesauri [ 11. However, each database has its own vocabulary and there is very little compatibility among these vocabularies even in similar subjects [2]. For example, the following terms were used by different vocabularies to denote the same concept: activation analysis, radiochemical analysis, radiometric analysis, chemical analysis by nuclear reactions, and scatter. Database vendors have provided the users with search terms postings through the use of online indexes. However, none of these tools provides information to the user concerning the relationships among the search terms or the equivalent terms. Another alternative for the user is to use free-text terms to search the database. However, many novice users do not realize that the free-text search only retrieves those references which contain exact match of the search terms. The user must think of all the synonyms and equivalent terms that might be used to designate the search terms. This is difficult for novice users, especially if they are not familiar with the terminology and there are no thesauri for that database. The number of databases which are produced without the use of thesauri or controlled vocabularies, seems to be increasing because it is less expensive to produce a free-text database than one using controlled vocabularies. However, the retrieval of information from these free-text databases will be more difficult, time consuming, and expensive for the user in the long run. Switching languages have the potential for resolving some of the problems caused by the lack of compatibility among the terminology used to designate a concept. A switching language could be used as an interface to transform a user’s search terms into the appropriate search terms of the vocabularies or databases to be used. The use of one experimental switching language for identifying the appropriate search terms of various vocabularies and the use of this information to determine the appropriate databases has been investigated [ 11. This switching language was the Vocabulary Switching System (VSS) developed by Battelle Institute [3]. VSS is an integrated vocabulary of twelve existing vocabularies. It can be considered a thesaurus of thesauri. The entire vocabularies for all the databases were merged and the linguistic or thesaural relationships existing in each thesaurus were preserved. A thesaural relationship model was developed to measure the degree of compatibility and switching capability of thesauri or vocabularies. This model, designated as the Compatibility and Switching Values (CSV), was tested using a variety of search terms. Groups of terms were matched with VSS to determine whether compatible and switching terms could be found in the different vocabularies. The CSV for each vocabulary was then calculated using the sum of the weighted values for each of the thesaural relationships identified as compatibility, hierarchical, or associative relationships. The VSS vocabularies were then ranked on the basis of their CSV for each group of terms. The following example illustrates the use of the switching vocabulary and the determination of the Compatibility and Switching Values (CSV) for six of the VSS vocabularies: CA, Chemical Abstracts Concept Edit File used for the CA Search online database; DOE, Department of Energy