The first large-scale evaluation of a "major operating information system." A detailed analysis of the performance of the Medical Literature and Analysis System (MEDLARS) in relation to 300 actual "demand search" requests made to the systems in 1966 and 1967. The objectives of the study were: (1) to study the demand search requirements of MEDLARS users, (2) to determine how effectively and efficiently the present MEDLARS service was meeting these requirements, and (3) to recognize factors adversely affecting the performance of MEDLARS. Digital facsimile from the National Library of Medicine at this link.