Selective Dissemination and Indexing of Scientific Information

Selective dissemination of information to individuals provides a new and promising method for keeping abreast of current scientific information. Since SDI services are directed to the information needs of each individual, they are a significant step beyond grouporiented services and products, which require considerable expenditure of effort by each user as he sorts useful information from trash. However, SDI systems do require a high degree of precision in matching scientists against documents. They must operate more efficiently and economically than many current systems which occasionally provide a useful item of information to users. To meet these stringent requirements for quality, precision, efficiency, and economy, more research must be devoted to comparing and improving indexing methods, which are the basic component of all information storage and retrieval systems. It is incredible that so much money has been spent on the development and operation of scientific information systems before basic data on the comparative performance of various indexing methods have been gathered, analyzed, and confirmed by multiple investigators. The design of an effective information system would seem to require this type of basic knowledge, just as basic properties of alternative materials must be known before an engineer can design a building, bridge, or factory. Yet, except for the few studies mentioned in the previous section, research on indexing methods has been greatly neglected. Bourne's comment about studies of indexing languages is still an appropriate description of the situation: "In almost all the experimental reports, the investigator worked with an indexing language different than that of other experimenters. Consequently, no one has ever had his test results verified, or expanded, or made more precise by another experimenter" (47). Most existing information systems are based on keyword indexing, with concepts broken into isolated terms during input operations and recombined to synthesize the original concept during search and retrieval. Such systems tend to involve imprecise indexing, with a high level of "noise" in retrieved documents, difficult search strategy involving extensive post-coordination, and lengthy, complex computer manipulations. This situation reflects the fact that many producers of indexed data originally focused the design of their systems on the production of a published product with entries printed under short, concise index heading