Some differences between three on‐line systems: impact on search results

With the growth in multiple on‐line search systems providing access to bibliographic data bases, exclusive availability of data bases is quickly disappearing. The searcher equally familiar with more than one system providing access to the same data base needs to apply some objective criteria in choosing a particular search system. Comparing three major search systems, we emphasize system differences in file structure, data fields and search features, and discuss how these differences influence search strategy and results. Results obtained from the CACondensates, ERIC, INFORM and NTIS data bases serve as examples for discussing the differences among the three search systems. Differences in postings among the systems are most often explained in terms of expected differences due to file structures, data fields and search features. Some unexpected differences between the systems are described and are assumed to be attributable to problems encountered during the preprocessing of the tape.