Library and Information Science

MEDLARS, an acronym of Medical Literature Analysis and Retrieval System, is a computer-based information system developed at the National Library of Medicine of the United States. It has been in operation since 1964, providing bibliographic services to the biomedical communities all over the world. It is in fact one of the largest and the oldest systems of this kind. However, its true significance lies in the fact that the system was subjected to a large-scaled evaluation study conducted in the period from 1966 through 1967 under the directorship of F.W. Lancaster, then the Information Systems Specialist of the National Library of Medicine. The principal objectives of the project were to study the demand search requirements of MEDLARS users and how effectively and efficiently the service was meeting these requirements, and also to recognize factors adversely affecting the performance of MEDLARS in hopes of providing suggestions for means by which the requirements of users can be satisfied more efficiently and economically as well. The test was designed to deter mine the operating efficiency of the specific aspects of MEDLARS: overall performance, coverage and processing, indexing, index language, searching and input and computer processing. The results of the test and analysis of failures are full of implications.

However, the present paper is concerned only with indexing, the intellectual factors which significantly affect the performance of all information retrieval systems. The MEDLARS indexing is practised by a group of indexers, some with sufficient experience and the others with little of it. As Robert Fairthorne stated, “indexing is the basic problem, as well as the costliest bottleneck of information retrieval.” This is particularly true when it is entirely depended upon the intellectual efforts of human indexers. With her own experience as a MEDLARS indexing instructor and reviser, the writer discusses MEDLARS indexing policies and practices as seen through the eyes of Lancaster in his evaluation test.