Record Display for the EPA National Library Catalog

RECORD NUMBER: 17 OF 33

OLS Field Name OLS Field Data
Main Title Clustering Criteria and Multivariate Normal Mixtures.
Author Symons, M. J. ;
CORP Author North Carolina Univ. at Chapel Hill. Dept. of Biostatistics.;Health Effects Research Lab., Research Triangle Park, NC.
Year Published 1981
Report Number EPA/600/J-81/698;
Stock Number PB86-208659
Additional Subjects Biostatistics ; Multivariate analysis ; Normal density functions ; Reprints ; Cluster analysis ; Covariance matrices ; Baysian analysis ; Maximum likelihood estimation
Holdings
Library Call Number Additional Info Location Last
Modified
Checkout
Status
NTIS  PB86-208659 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 06/21/1988
Collation 11p
Abstract
New clustering criteria for use when a mixture of multivariate normal distributions is an appropriate model are presented. They are derived from maximum likelihood and Bayesian approaches corresponding to different assumptions about the covariance matrices of the mixture components. Two of the criteria are modifications of the determinant of the within-groups sum-of-squares criterion of Friedman and Rubin (1967, Journal of the American Statistical Association 63, 1159-1178); these criteria appear to be more sensitive to disparate cluster sizes. Two others are appropriate for different-shaped clusters. The practical aspects of these criteria, and of another one studied by Maronna and Jacovkis (1974, Biometrics 30, 499-505) for heterogeneous covariance matrices, are outlined. An example involving the separation of two types of diabetic patients from normal subjects, each group having a distinct covariance structure, is given. The results with the three criteria appropriate for different-shaped clusters were comparable to one another and preferable to those obtained with the three criteria for similar-shaped clusters. Results obtained for the example with two additional clustering procedures are presented.