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)

The Schools and Staffing Survey (SASS) represents the first time the National Center for Education Statistics has integrated three of the Elementary and Secondary Education Surveys: the Teacher Demand and Shortage Surveys, Public and Private School Surveys, and Teacher Surveys. The SASS was designed to measure the critical aspects of teacher…