Chapter H - Selective Dissemination of Information

Abstract

Selective Dissemination of Information (SDI) service is a type of “alerting service” meant for individual users, mainly specialists, which is exclusively restricted to the area of interest of the user concerned. An SDI system is mainly based on two types of profiles—users’ profiles and document profiles—which are matched to decide about the relevance of any new document for an individual user. The needs and interests of each user or a user group having similar interests are ascertained and carefully analyzed. These are then expressed in some keywords or code numbers. The individual profiles are maintained in a users’ profile file. As the documents come to the library, their contents are clearly analyzed and the unit concepts or facets are expressed in the same keywords, symbols, or code numbers which have been used in users’ profiles and the individual profiles are maintained in a documents profile file. The two profile files are matched at regular intervals. When positive results are obtained, that is, a close resemblance between a user’s profile and document profile is found, the necessary details from both the profiles are recorded. Intimation is sent to a particular user, with whose profile the profile of a document matches closely. An SDI system has a mechanism for feedback from the side of users. It was H.P. Luhn who first spelt out his idea of SDI and he visualized the use of computer in SDI service. But in practice, the operation of an SDI system can also be done manually.