Library and Information Science

The mode of literature searching currently used almost exclusively by large mechanized retrieval systems is one-chance delegated search. In this type of search, the information need is delegated by the person having the information need to a second individual who prepares searching strategy and formulation, and a number of searches are batched and processd simultaneously. The searcher has little opportunity to browse on behalf of the requester as he does in the conventional manual literature searching. It is obvious that with this type of searching mode a very clear and detailed statement of the requester’s information need is prerequisite to the successful search. Then, it leads to assume that the interface between the user and the system will importantly affect the performance of a large mechanized retrieval system. The present paper is concerned with question of user-system interaction of a large mechanized retrieval system as observed in the evaluation study of MEDLARS conducted at the National Library of Medicine of the United States. The significance of user-system interaction is well illustrated by the results of the study. It is indicated that 25% of all the recall failures and 16.6% of all the precision failures are attributed to undesirable interaction between the user and the system. A recall failure due to defective interaction is mainly attributable to the system. A recall failure due to defective interaction is mainly attributable to the request statement which is more specific than the actual area of information need. On the other hand, a precision failure is due to a request statement which is more general than the actual information need. The importance of a request statement that explicitly delineates the actual information need is sufficiently emphasized.