The Validity of the Inverse Scree Test for Cluster Analysis
Richard G. Lathrop, Janice E. Williams · Educational and Psychological Measurement · 1990
A Monte Carlo study of the validity of the Inverse Scree test under conditions where true group membership is known was presented. Four distributions involving 2, 3, 4, and 5 true groups of 3,000 computer "subjects" were generated using nonredundant measurement on four orthogonal variables. A fifth Low-N distribution for 3 true groups was also generated. Fifty cluster analyses of each distribution were analyzed both by the JE(2)/JE(l) mathematical criterion and by four raters using the Inverse Scree technique. The results indicated that JE(2)/JE(l) is markedly N-dependent and that Inverse Scree tests are affected by large numbers of true groups. Implications for the data analyst are discussed.