Develops an approach for advance estimation of user charges based on information actually retrieved by searching numeric databases, and defines a method for query cardinality estimation. Based on the relational data model, which uses relational algebra, this method uses formal file descriptions to describe the database files. (LRW)

Describes experiment designed to assess information value for individual searchers in realistic search environment. Included in data analysis are comparison of two alternative retrieval methods, evaluation of how well humans are able to estimate document relevance, and investigation of value function components (features and coefficients) and…