On deriving design equations for information retrieval systems
William S. Cooper · Journal of the American Society for Information Science · 1970
Abstract In recent research on document retrieval systems, considerable attention has been devoted to the problem of defining appropriate performance measures, but very little has been done to derive design equations that make use of them. Design equations show the relationships that obtain between retrieval performance and the design characteristics of the system under analysis. Because design equations, when and if they become available, will be the keystones of retrieval system theory, the question of how they can be derived is an important one. In this paper, the question is investigated in three case studies corresponding to three different types of retrieval systems. A design equation is derived for each of the three system types, the equation in each case showing the relationship between expected search length, used as a performance measure, and certain system characteristics having to do with the distribution of index terms over the document collection and the number of errors in the search requests.