Generalizability of scores influenced by multiple sources of variance

Generalizability theory concerns the adequacy with which a universe score can be inferred from a set of observations. In this paper the theory is applied to a universe in which observations are classifiable according to two independent variable aspects of the measuring procedure. Several types of universe scores are developed and the variance components ascertained for each type. The composition of expected observed-score variance and the adequacy of inference to a particular type of universe score is a function of the procedure used in gathering data. A generalizability study provides estimates of variance components which can be used in designing an efficient procedure for a particular decision purpose.This study was conducted under Grant M-1839 from the National Institute of Mental Health while the authors were on the staff of the University of Illinois. Dr. Rajaratnam shared responsibility for the technical report of July, 1961 on which this paper is based. The present revision was made subsequent to her death in 1963. The present addresses of the other authors are: Goldine C. Gleser, Department of Psychiatry, Central Clinic, Cincinatti, 29, Ohio; Lee J. Cronbach, School of Education, Stanford University.