Search

There is no doubt that the availability of machine‐readable information products accessible by online means is posing a threat to the existence of printed information products. The reason is not that there is no longer a place for printed products, but that the shifting pattern of available products and usage is making it difficult to find the ‘right’ pricing structure. If the producer gets the pricing structure wrong, then the whole product—printed, machine‐readable or otherwise—is in jeopardy.

Chemical Abstracts Issues and Indexes have been available in printed form since 1907. Microform versions are also available now. In the near future Chemical Abstracts material will be accessible by computer in the UK via six on‐line systems and one batch current awareness system. This variety of modes of access is further diversified by the variety of ways in which the original Chemical Abstracts Service (CAS) files have been implemented for use with the different search systems, and by the differences in the system facilities, pricing structure and technical back‐up offered by the service suppliers. This paper attempts to bring together in tabular form factors which should be considered in taking rational decisions on how to get the ‘best’ out of Chemical Abstracts material, the ‘best’ being the optimum performance/cost ratio for any given topic.

The requirements for producing a current database, Chemical Business NewsBase (CBNB), updated weekly, including the data content, are briefly outlined. The use of BASIS for data capture, validation, manipulation, and output of the data is discussed with particular reference to the features which support the human element in production and which are used for quality control. Routine production and distribution of CBNB are further examined.

This paper describes part of the Chemical Abstracts Condensate Evaluation (CAC Evaluation) carried out by the United Kingdom Chemical Information Service (UKCIS).

A selected sample of U.K. University, industrial and Government scientists were given a current-awareness service for 18 months, in order to investigate the practicability and problems of such a service. Six hundred profiles were run, using the natural-language data bases Chemical Titles and Chemical-Biological Activities produced by Chemical Abstracts Service. Precision and recall were measured, and correlations between profile performance and such factors as subject area and profile logic were investigated statistically. Precision and recall failures were analysed and various improvements to the system were suggested as a consequence. It was concluded that a viable computerised current-awareness service based on searching natural language could be created.

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.