Dear all, Determine the number of components in Principal Component Analysis decomposition is usually a hard work, close to an art. Recently Malinowski discuss some methods in a paper that is proposed a new method (DRMAD): DOI: 10.1002/cem.1182 This last method has in the program developed by Carmelo Prestipino PCA_GUI.py (http://code.google.com/p/prestopronto/) developed with some advices of Marcos Fernandez-Garcia. There are many methods better than use the empirical IND funtion. The better is have a good knowledge of your system by other techniques or by the behavior, this additional information can be of the extreme importance if you have more than 2 components. Best regards, Santiago -------------------------------------------- Dr. Santiago J. A. Figueroa Pesquisador - Laboratório Nacional de Luz Síncrotron (LNLS) Centro Nacional de Pesquisa em Energia e Materiais (CNPEM) Rua Giuseppe Máximo Scolfaro, 10000 Caixa Postal 6192 - CEP 13083-970, Campinas(SP), BRASIL Tels.: (sala)19 3517-5063 / (xafs2)19 3512-1246 / (xafs1)1139 / (dxas)1141 Fax: 19 3512-1006 WEB: http://www.lnls.br BLOG: http://www.marevero.blogspot.com/