## Edmond Malinvaud (1923-2015)

Posted in Books, Kids, Statistics, University life with tags , , , , , , , , on March 11, 2015 by xi'an

The statistician, econometrician, macro- and micro-economist, Edmond Malinvaud died on Saturday, March 7. He had been director of my alma mater ENSAE (1962–1966), directeur de la Prévision at the Finance Department (1972–1974), director of INSEE (1974–1987), and Professeur at Collège de France (1988–1993). While primarily an economist, with his theories of disequilibrium and unemployment, reflected in his famous book Théorie macro-économique (1981) that he taught us at ENSAE, he was also instrumental in shaping the French econometrics school, see his equally famous Statistical Methods of Econometrics (1970), and in the reorganisation of INSEE as the post-war State census and economic planning tool. He was also an honorary Fellow of the Royal Statistical Society and the 1981 president of the International Institute of Statistics. Edmond Malinvaud studied under Maurice Allais, Nobel Prize in economics in 1988, and was himself considered as a potential Nobel for several years. My personal memories of him at ENSAE and CREST are of a very clear teacher and of a kind and considerate man, with the reserve and style of a now-bygone era…

## Le Monde puzzle [#869]

Posted in Books, Kids, Statistics, University life with tags , , , , , , , , , on June 8, 2014 by xi'an

An uninteresting Le Monde mathematical puzzle:

Solve the system of equations

• a+b+c=16,
• b+c+d=12,
• d+c+e=16,
• e+c+f=18,
• g+c+a=15

for 7 different integers 1≤a,…,g9.

Indeed, the final four equations determine d=a-4, e=b+4, f=a-2, g=b-1 as functions of a and b. While forcing 5≤a, 2b≤5, and  7a+b≤15. Hence, 5 possible values for a and 4 for b. Which makes 20 possible solutions for the system. However the fact that a,b,c,d,e,f,g are all different reduces considerably the possibilities. For instance, b must be less than a-4. The elimination of impossible cases leads in the end to consider b=a-5 and b=a-7. And eventually to a=8, b=3… Not so uninteresting then. A variant of Sudoku, with open questions like what is the collection of the possible values of the five sums, i.e. of the values with one and only one existing solution? Are there cases where four equations only suffice to determine a,b,c,d,e,f,g?

Apart from this integer programming exercise, a few items of relevance in this Le Monde Science & Medicine leaflet.  A description of the day of a social sciences worker in front of a computer, in connection with a sociology (or sociometry) blog and a conference on Big Data in sociology at Collège de France. A tribune by the physicist Marco on data sharing (and not-sharing) illustrated by an experiment on dark matter called Cogent. And then a long interview of Matthieu Ricard, who argues about the “scientifically proven impact of meditation”, a sad illustration of the ease with which religions permeate the scientific debate [or at least the science section of Le Monde] and mingle scientific terms with religious concepts (e.g., the fusion term of “contemplative sciences”). [As another “of those coincidences”, on the same day I read this leaflet, Matthieu Ricard was the topic of one question on a radio quizz.]