SCIENTIFIC PAPERS OF TJALLING C. KOOPMANS, Vol. 1

Springer-Verlag, 1970

Preface

Tjalling Koopmans has made fundamental contributions to three major areas of modern quantitative economics. The first is the statistical identification and estimation of parameters in econometric models. The second is activity analysis, of which what is popularly known as linear programming is one aspect. The third is intertemporal utility maximization and the optimum allocation of resources over time. Most economists would be pleased to make seminal contributions in just one area as he has done in each. In making our selection of his papers to be included in this volume, we have attempted to include significant contributions in each of the major areas of Koopmans' work.

We have tried as well to give some idea of the extraordinary breadth of the man and his work. It is for this reason that we have included one of his two published papers in physics, "Über die Zuordnung von Wellenfunktionen und Eigenwerten zu den einzelnen Elektronen eines Atoms", a paper which is still referred to in basic physics texts. Although we were greatly tempted to include a major portion of Koopmans' Ph.D. dissertation in mathematical statistics at the University of Leiden, we found that the entire dissertation was far too long and that a meaningful sub-section was difficult to extract because of the relative unfamiliarity of the basic approach to modern readers. Again both length and difficulty of condensation precluded inclusion of material from Tanker Freight Rates and Tankship Building, a careful empirical investigation into a problem of considerable contemporary significance.

As a matter of principle, we have excluded material originally published as part of Cowles Commission Monographs or in Koopmans' recent book, Three Essays on the State of Economic Science, since these volumes are readily available and easily accessible. The remaining papers reprinted here represent our personal tastes to a considerable extent, subject to our desire to include as representative a selection of his work as possible. We have, however, included as complete a bibliography as we were able to reconstruct with the help of Truus Koopmans.

Both at the University of Chicago and at Yale University, Koopmans has inspired several "generations" of students and colleagues. He has not only advanced, and continues to advance, the frontiers of quantitative economic knowledge but he serves as a source of inspiration, encouragement, and substantive help to all of those who come in contact with him. It was during Koopmans' eleven years with the Cowles Commission for Research in Economics at the University of Chicago, from 1944 to 1955,that the compilers of this volume first came to know him. We found him to be a rather quiet man, deeply dedicated to his work, to his students, and to his colleagues. He thinks and works in very precise terms. His appreciation of the beauty and elegance of abstract logical structure is expressed not only in his economic analysis but in his graceful musical compositions. The precision of thought, the modesty and creativity of the man, and his selfless dedication to the advancement of knowledge have inspired us all. These qualities of the man are apparent, we think, in everything he writes as well as in his personal and professional life.

Tjalling Koopmans was born on August 28, 1910 at 's Graveland, a small town near Hilversum, in the Netherlands. He was the youngest son of Sjoerd Koopmans and Wijkje van der Zee Koopmans. One elder brother, Jan, became a minister, and the other, Hendrijk, an engineer. Koopmans' education began at the school of which his father was headmaster. Later, he studied at the University of Utrecht, receiving the M. A. degree in physics and mathematics in 1933. He went on to the University of Leiden, where his important dissertation, Linear Regression Analysis of Economic Time Series, won him the Ph.D. degree in mathematical statistics in 1936. In that year he married Truus Wanningen. They have three children, Ann, Henry, and Helen.

From 1936 until 1938, Koopmans was a lecturer at the Netherlands School of Economics in Rotterdam, an institution which was to give him an honorary degree some twenty-five years later in 1963. In 1938, Koopmans accepted a position as an economist with the League of Nations in Geneva. The League of Nations had sponsored Tinbergen's pioneering studies of business cycles and published his famous econometric model of the U.S. economy. In his contact with Tinbergen, his work at the League, and in his own study of tanker freight rates and the cycle in ship building, Koopmans developed a lasting appreciation of the problems, difficulties and rewards of empirical work, which deeply influenced his later work on econometric methods. Moreover, he has consistently and emphatically conveyed to his colleagues and students his sense of the importance of careful and rigorous empirical inference.

In 1940 Koopmans accepted a post as Research Associate at Princeton University in the United States for the year 1940-1941, and also was Special Lecturer at New York University's School of Business. The following year he served as Economist for the Penn Mutual Life Insurance Company in Philadelphia. From 1942 to 1944 he was Statistician for the Combined Shipping Adjustment Board. During these years he met Trygve Haavelmo and Jacob Marschak, who brought him to the Cowles Com-mission for Research in Economics at the University of Chicago in 1944.In 1946 he was appointed Associate Professor at the University of Chicago, and in 1948, Professor. He remained until 1955 when the entire Cowles group moved to Yale University.

He was Cowles' Research Director from 1948 to 1954 at Chicago, and its Director at Yale from 1961 to 1967. He is presently Alfred Cowles Professor of Economics at Yale.

Among his many honors and distinctions are two honorary degrees, one from the Netherlands School of Economics (1963) and another from the Catholic University of Louvain (1967). He has been Vice President (1949) and President (1950) of the Econometric Society and Vice President (1966) of the American Economic Association. In 1960-1961 he was Frank W. Taussig Research Professor of Economics at Harvard University.

We have had the benefit of advice from George Borts, Charles Holt, and Stanley Reiter in making our selection of papers included here. It is an honor and a pleasure for us to present this collection of reprints of selected articles by Tjalling Koopmans on the occasion of his sixtieth birthday.

Martin Beckmann
Carl F. Christ
Marc Nerlove