Quality and Quantity, 14 (1980) 127-742 727 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands HOW SIMILAR ARE THE DIFFERENT RESULTS? ZVI MAIMON Seker Consultants Ltd., and The Department of Sociology, Tel-Aviv University, Tel-Aviv, Israel ITZHAK VENEZIA Hebrew University, Jerusalem, Israel, and The University of Rochester, Rochester, New York, U.S.A. JAMES C. LINGOES Department of Psychology, The University of Michigan, Ann Arbor, Michigan, U.S.A. Introduction An increasing number of studies in the social sciences utilize Small- est-Space Analysis-I (SSA-I) (e.g., Laumann and Guttman, 1966; Schle- singer and Guttman, 1969; Levy and Guttman, 1975a, b; Elizur and Guttman, 1976; Levy, 1976; Guttman and Guttman, 1976; Ben-Sira, 1977; Maimon, 1978). This paper deals with some aspectsof compar- isons between SSA-I results, and analyzes existing methods for com- paring two or more SSA-I solutions obtained from different popula- tions or from different samples of the same population. Alternative measures of the degreeof similarity between the various solutions are also discussed. We begin by very briefly discussingthe SSA-I technique. Then, we move to the questions involved in comparing SSA-I solutions. A par- ticular technique for comparison, PINDIS, is then explained in some detail. Finally, the results of an empirical study utilizing four SSA-I solutions are analyzed by PINDIS and by other approaches. Smallest-Space Analysis-I (SSA-I) The SSA-I technique (or algorithm) is a member of a family of SSA techniques developed by Guttman (1968) and Lingoes (1973), which 0033~5177/80/0000-0000/$02.25 Q 1980 Elsevier Scientific Publishing Company