COMPARATIVE EFFICIENCY OF SEARCHING TITLES, ABSTRACTS, AND INDEX TERMS IN A FREE‐TEXT DATA BASE Available to Purchase

The choice of a suitable data base for providing an information service is governed by factors of coverage, performance, and cost. The cost of the data base to subscribers is a known quantity, and the coverage is decided by the data base producers. This paper describes an investigation into the relative performance of the four major Chemical Abstracts Service magnetic tape data‐bases, Chemical Titles (CT), which contains the titles of citations only, Chemical Abstracts Condensates (CAC), which contains titles enriched with keyword phrases, Chemical‐Biological Activities (CBAC), and Polymer Science and Technology (POST), both of which contain full digests in addition to titles. The performance was measured in terms of the relative currency of the four data‐bases, and the retrieval efficiency of profiles searched against them. Fifty questions from industrial and government research organizations were used in the experiment. Search profiles corresponding to these questions were constructed for searching against each data‐base, output was assessed for relevance by users, and profile performance figures (precision and recall ratios) were calculated for each profile. The overall retrieval efficiency of profiles searched against data‐bases containing titles only, titles‐plus‐keywords, and titles‐plus‐digests, was calculated, and these results are presented.