Explicit and implicit variables in information retrieval (IR) systems
Stephen E. Robertson · Journal of the American Society for Information Science · 1975
Abstract Cleverdon's “inverse relationship between recall and precision” and other relationships between the measures of performance of retrieval systems, arise from variations in other (independent) system variables. This paper explores the properties of these independent variables, and defines a class of basic variables named M‐factors. The “inverse relationship” is generated by variations in a single M‐factor, but does not always obtain if more than one M‐factor is allowed to vary. A number of examples are discussed in the light of this analysis. The possibility is suggested that all variables affecting the performance of retrieval systems can be decomposed into M‐factors. The implications of these ideas for laboratory tests on retrieval systems are discussed. A mathematical treatment of the ideas is also given.