ACADEMIC PRESS RAPID MANUSCRIPT REPRODUCTION Proceedings of a NA TO Advanced Study Institute on Discriminant Analysis and Applications Athens, Greece June 8-20, 1972 DISCRIMINANT ANALYSIS AND APPLICATIONS Edited by T. CACOULLOS UNIVERSITY OF ATHENS ATHENS, GREECE Academic Press New York and London 1973 A Subsidiary of Harcourt Brace Jovanovich, Publishers COPYRIGHT © 1973, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED. NO PART OF THIS PUBLICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT PERMISSION IN WRITING FROM THE PUBLISHER. ACADEMIC PRESS, INC. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. 24/28 Oval Road, London NW1 Library of Congress Cataloging in Publication Data NATO Advanced Study Institute on Discriminant Analysis and Applications, Athens, 1972. Discriminant analysis and applications. Proceedings of the conference held June 8-20, 1972. Bibliography: p. 1. Discriminant analysis-Congresses. I. Cacoullos, Theophilos, ed. II. Title. QA278.65.N37 1972 519.5'3 73-806 ISBN 0-12-154050-2 PRINTED IN THE UNITED STATES OF AMERICA In memory of PRASANTA CHANDRA MAHALANOBIS (1893-1972) CONTRIBUTORS J.A. Anderson, Department of Biomathematics, University of Oxford, Oxford, England T.W. Anderson, Department of Statistics, Stanford University, Stanford, California D.F. Andrews, Department of Mathematics, University of Toronto, Toronto, Ontario, Canada T. Cacoullos, Statistical Unit, University of Athens, Athens, Greece Somesh Das Gupta, School of Statistics, University of Minnesota, Minneapolis, Minnesota M.M. Desu, Department of Statistics, State University of New York, Buffalo, New York W.J. Dixon, Department of Biomathematics, University of California, Los Angeles, California Daniel Dugue, Institut de Statistique, Universite de Paris, Paris, France S. Geisser, School of Statistics, University of Minnesota, Minneapolis, Minnesota R.I. Jennrich, Department of Biomathematics, University of California, Los Angeles, California M.G. Kendall, Scientific Control Systems Ltd., London, England Peter A. Lachenbruch, Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina Kameo Matusita, Institute of Statistical Mathematics, Tokyo, Japan J. Michaelis, Institut für Medizinische Statistik und Dokumentation der Universität Mainz, Mainz, West Germany Elliott Nebenzahl, Department of Statistics, California State University, Hay ward, California ix CONTRIBUTORS R.A. Reyment, Paleontologiska Institut, Uppsala Universitet, Uppsala, Sweden Willem Schaafsma, Mathematisch Instituut, Risj Universiteit, Groningen, The Netherlands Rosedith Sitgreaves, Department of Statistics, California State University, Hay ward, California Milton Sobel, School of Statistics, University of Minnesota, Minneapolis, Minnesota George P. H. Styan, Department of Mathematics, McGill University, Montreal, Quebec, Canada J. Tiago de Oliveira, Faculdade de Ciências Matemâtica, Lisbon, Portugal X PREFACE This book comprises the proceedings of the NATO Advanced Study Institute on Discriminant Analysis and Applications held in Kifissia, Athens, Greece, June 8-20, 1972. Participants in the Institute came from almost all NATO countries; there were 19 lecturers and 60 additional participants. It was unfortunate that Professor C. R. Rao was unable to participate due to the serious illness of P. C. Mahalanobis during those days; Mahalanobis died on June 28, 1972. In memoriam and appreciation of his pioneering contribu- tions in the field of discriminant analysis, this volume is dedicated to Prasanta Chandra Mahalanobis (1893-1972), founder of the Indian Statistical Institute and of Sankhyä. The term discriminant analysis in the title of these Proceedings is an alternative to the term classification which is used as a synonym for discrimi- nation by many statisticians. This choice is to avoid ambiguity, since classifi- cation is often also used in the sense of taxonomy or construction of classes. For a discussion of these differences the reader is referred to the paper by Professor M. G. Kendall in this volume. Both theory and applications are discussed. A comprehensive survey and a historical development of discriminant analysis methods are given in the review paper by Professor Somesh Das Gupta. Here the reader will also find a fairly extensive up-to-date bibliography arranged by subject matter and then chronologically within subject matter. This bibliography contains articles and books published up to 1972 and some unpublished papers as well. At the end of this book, there is a bibliography, presumably exhaustive, with authors in alphabetical order, prepared by Professor G. P. H. Styan (McGill University) and the Editor. It includes papers published up to 1971 and books up to 1972. Several papers deal with the exact, asymptotic, and empirical (Monte Carlo) evaluation of the probabilities of misclassification, especially under the assumption of normal alternative populations with the same or different dispersion matrices. Logistic and quasi-linear discrimination are also covered. Distance functions are considered especially as regards discrimination in the Gaussian case. Applications, particularly in medicine and biology, are also discussed in some of these papers. Moreover, computer graphical analysis and XI PREFACE graphical techniques for multidimensional data are discussed and illustrated by examples in two papers. It is regretted that final versions of the papers by Professors Ingram Olkin (Stanford University) and M. S. Srivastava (Univer- sity of Toronto) did not arrive in time to be included in these Proceedings. I wish to thank the Scientific Directors of the Institute, Professors T. W. Anderson and M. G. Kendall, for their encouragement and suggestions throughout the organization of the Symposium. Thanks are also due to my Assistants at the University of Athens, Ch. Charalambides, Urania Chrys- aphinou, A. Dallas, and Amalia Veini, for their assistance with the local arrangements and for carrying out the correspondence for the Institute. The editing of this book was completed during my visit at McGill University. Special thanks go to my colleague G. P. H. Styan for valuable suggestions; to Leslie Ann Hathaway for helping with proofreading and the compilation of the bibliography at the end of this volume, I express my sincere appreciation. I am particularly grateful to Maria Lam for patiently preparing the difficult typescript; she did a superb job. Thanks are also due to the contributors for their cooperation and to Academic Press whose interest in publishing these Proceedings was expressed in the early stages of the Institute. It goes without saying that the Institute would not have materialized without the financial support of the NATO Science Committee. I also acknowledge with gratitute the support of the Greek Ministry of Culture and Science for sponsoring the social activities of the Institute, by no means less contributory to its success. T. Cacoullos Xll INTRODUCTORY ADDRESS* T. Cacoullos Director of the NATO Advanced Study Institute on Discriminant Analysis and Applications In a NATO report on nonmilitary cooperation issued in 1956, discuss- ing science and technology, the three foreign ministers of Canada, Italy, and Norway recommended the creation of an ad hoc working group to study topics of special importance to NATO and specifically the way in which the Organization might support or supplement the scientific activities of other organizations. A Task Force was formed in June 1957 to consider these recommendations. The psychological shock of the launching of the first Soviet Sputnik in October 1957 resulted in the immediate presentation of the Task Force's Report to the Heads of Governments of the Alliance at their meeting in December 1957. The recommendations of the former were accepted and both a Science Adviser and a Science Committee were ap- pointed to follow up the proposals of the Task Force. The Science Committee met first in March 1958 and ever since its activities have grown to significant proportions. Its programs of Fellowships, Research Grants, and Advanced Study Institutes have contributed a great deal to the promotion of common understanding and cooperation between the scientific communities of NATO members. The Advanced Study Institutes Program has been sponsoring about 50 Advanced Study Institutes annually since 1959. The Study Institutes, or Summer Schools as they are called, range in subject from mathematics and physics through biological and medical topics to such areas as psychological measurement theory and programming languages for computers. The prin- cipal feature of such meetings is the bringing together of research workers, often in secluded surroundings, for about two weeks to study a specific topic. It is exactly within this framework that the present Institute on Discriminant Analysis and Applications was organized. It is therefore with pleasure that we acknowledge the support of the NATO Science Committee which made this meeting possible. *Read at the Opening Ceremony, June 8, 1972. xiii INTRODUCTORY ADDRESS On behalf of the participants I should also express our appreciation to the Greek Ministry of Culture and Science for its cosponsoring of the Institute; in particular, most of its social activities which include tonight's cocktails and buffet dinner, the Delphi excursion this coming Sunday, and the Hydra-Aegina cruise next weekend. We are honored by the presence of his Exellency, the Minister of Culture and Science, Mr. C. A. Panayiotakis, who has accepted my invitation to deliver the opening address of the Institute. Before I introduce his Excellency, the Minister, allow me to spend a few minutes introducing the Institute's topic. Discriminant analysis, other- wise known as classification theory, is one of the most important areas of multivariate statistical analysis. A statistical discrimination or classification problem consists in assign- ing or classifying an individual or group of individuals to one of several known or unknown alternative populations on the basis of several measure- ments on the individual and samples from the unknown populations. In the simplest case of two normal populations, for example, a linear combination of the measurements, called linear discriminator or discriminant function, is constructed, and on the basis of its value the individual is assigned to one or the other of the two populations. This decision process involves two kinds of error, namely, that the individual is assigned to population No. 2 while it really belongs to population No. 1 and vice versa. The researcher wishes to minimize in some sense the chances of a wrong decision. R. A. Fisher was the first to suggest the use of a linear discriminant function in 1936. Its early applications led to some important anthropométrie discoveries such as sex differences in mandibles, the extraction from a dated series of the particular compound of cranial measurements showing secular trends, and solutions of taxonomic problems in general. At about the same time that Fisher introduced the discriminant func- tion, Mahalanobis (in India) proposed his generalized distance which was applied with success to craniometric and other anthropological studies. Let us mention a few of the early applications of discriminant analysis. Professor C. R. Rao, Director of Research and Training at the Indian Statistical Institute, considered the assignment of an individual to one of the three Indian castes, Brahmin, Artisan, or Korwa, on the basis of four measurements, namely height, sitting height, nasal depth, and nasal height. More details about this and other applications can be found in the well- known multivariate analysis textbooks of two distinguished participants of the present Institute, Professors T. W. Anderson of Stanford University and M. G. Kendall, formerly of the University of London, now Chairman of Scientific Control Systems, whom we are happy to have with us in the role of Scientific Directors and Lecturers for the Institute. xiv