Sargan was born in Barnsley, Yorkshire. His early ability at mathematics won him a place at Doncaster Grammar School and gained him a State Scholarship for entrance to St John's College, Cambridge, where he pursued the Mathematical Tripos, becoming a Senior Wrangler. He joined the Scientific Branch of the Civil Service during the Second World War, but, on a visit to a bookshop towards the end of the war, he came across John Maynard Keynes's General Theory of Employment, Interest and Money (1936). He was so struck with Keynes's ideas for tackling mass unemployment that he took up economics on returning to Cambridge after the war, and completed a degree in Economics in one year.
His career began as a Lecturer in Economics at Leeds University, where he commenced research into the distribution of wealth, duopoly, production, and growth, and statistical time-series problems (comparing several series of data over a period of time). During a visit to the Universities of Minnesota and Chicago, his interests focused on the econometric theory of estimating economic models from time-series data, and he rapidly established a reputation for insightful, rigorous and powerful analyses. This research was published in Econometrica, the prestigious journal of the Econometric Society, and he was elected to a Fellowship of the Econometric Society in 1963. He came to the London School of Economics in 1964 as a Reader in Statistics, joining A.W.H. (Bill) Phillips (of the Phillips machine and Phillips curve) and Jim Durbin; a Professorship in the Economics Department followed in 1965.
His appointment took the LSE group to the technical forefront in research. Perhaps as importantly, he helped attract a vibrant group of young faculty and many able students to the redesigned MSc in Econometrics. This achieved new heights of advanced teaching, and Denis Sargan can be credited with the creation of a generation of econometricians trained to highly technical levels in all aspects of quantitative economics, adopting what is loosely called the "LSE approach to econometric modelling".
His teaching would not please the current vogue for assessing "quality": from a few notes, the most arcane mathematics would flow with inadvertent changes of notation, and key steps treated as obvious. The effect was to force his students to rework the material completely - from which ensued understanding and technical expertise that would last a lifetime. He is remembered with awe as well as affection for the penetrating solutions he suggested after a few moments' thought on a problem that a student or colleague had struggled with for several weeks. Often he just pulled open a desk drawer and handed out his unpublished earlier analysis of the problem at hand. His modesty camouflaged a brilliant and creative mind, whose greatest difficulty was to comprehend how little most of us really knew.
By 1984, when he took early retirement, he had supervised more than 30 successful doctorates. His past students currently occupy Chairs at a host of the world's distinguished universities, including LSE, Oxford, Yale, Madrid, the European University Institute in Florence, and Athens.
His empirical research complemented and motivated much of his theoretical work. His paper for the Colston Society conference at Bristol University in 1963, published in its proceedings in 1964, initiated the modern approach to time-series econometric modelling.
Sargan can be credited with the conceptual foundations of that approach, the introduction of what has since become the dominant model form, and the technical solution of several of the key specification problems. The analytical apparatus was applied to the intractable problem of 1960s wage- price inflation, and Sagan highlighted the role of real-wage resistance in wage bargains that was to prove a stumbling block for incomes policies. In workshops, he and Bill Phillips would debate the relative merits of that model versus the Phillips curve, and both questioned the existence of any "trade-off" between inflation and unemployment.
Election as President of the Econometric Society came in time for its 1980 World Congress at Aix-en-Provence. Sargan was made a Fellow of the British Academy in 1981, and an honorary foreign member of the American Academy of Arts and Sciences in 1987.
He and his wife Mary Millard, whom he married in 1953, entertained most hospitably at their home, fostering a friendly atmosphere at the School. He was a keen gardener, and talked as freely about his hobby while at the LSE as he did about econometrics.
John Denis Sargan, economist: born Barnsley, Yorkshire 23 August 1924; Assistant Lecturer, Lecturer and Reader, Leeds University 1948-63, Reader 1963-64; Professor of Econometrics, London School of Economics 1964-84, Tooke Professor of Economic Science and Statistics 1982-84 (Emeritus); FBA 1981; married 1953 Mary Millard (two sons, one daughter); died Theydon Bois, Essex 13 April 1996.