I just learned that Paul Deheuvels died last week. He was head of the statistics department at Université Pierre & Marie Curie when I was a lecturer there (1987-1992). And a professor of statistics and probability there for his entire career, from 1974 to 2013. While we were working on completely different topics, and had divergent political views, we kept an amicable connection throughout the years, as we were living close enough to meet once in a while at the local farmers’ market and have a quick chat. When I was considering my options for pursuing a PhD, while writing a Master thesis on commutative Lie algebras with his father, René Deheuvels, he was one of the people who offered to supervise me (on a topic related with empirical processes, which were his forte). Later, he suggested I wrote a very short introduction to Bayesian statistics in the Que sais-je? collection (where he published three books) and, when my manuscript was found too theoretical, he proposed to publish an expanded version in the Economica collection, which ended up being the French version of The Bayesian Choice. I also remember a very kind email he sent me while I was recovering from my climbing accident, in 2013, as a fellow climber. (For a long while, he would drive to Fontainebleau once or twice a week for bouldering.) As alluded (to) above, Deheuvels’ political views were very conservative, with a proximity to the far-right Club de l’Horloge and a mix of vieille France traditionalism and libertarianism positions. For sure, he never was shy from embarking in controversies, from defending Allègre’s climato-scepticism to backing Séralini’s controversial study on the cancerogenic effects of Mosanto’s transgenic maize.
Archive for climatosceptic
Paul Deheuvels (1948-2026)
Posted in Books, Mountains, University life with tags Bayesian Choice, Bayesian statistics, Book, bouldering, Bourg-la-Reine, climatosceptic, climbing accident, Club de l'Horloge, Economica, empirical process, Fontainebleau, functional estimation, Jussieu, Monsanto, obituary, Paris, Paris 6, Paul Deheuvels, Que sais-je?, The Bayesian Choice, thumb, transgenic corn, UMPC, Université Pierre et Marie Curie on February 5, 2026 by xi'anscience inverse [cover]
Posted in pictures, Travel, University life with tags @ScientistTrump, Albert Einstein, anti-scientism, arbitrariness, baby Trump, climatosceptic, Columbia University, cover, firing, Food and Drug Administration, Libé, National Institute of Health, Trump administration, US politics on April 10, 2025 by xi'an
Le Monde on E. Wegman
Posted in Statistics with tags climate change, climatosceptic, computational statistics, CSDA, Ed Wegman, Michael Mann, plagiarism on December 31, 2011 by xi'an
In addition to the solution to the wrong problem, Le Monde of last weekend also dedicated a full page of its Science leaflet to the coverage of Michael Mann’s hockey curve of temperature increase and the hard time he has been given by climato-skeptics since its publication in 1998… The page includes an insert on Ed Wegman’s 2006 [infamous] report for the U.S. Congress, amply documented on Andrew’s blog. And mentions the May 2011 editorial of Nature on the plagiarism investigation. (I reproduce it above as it is not available on the Le Monde website.)
València 9 snapshot [1]
Posted in Mountains, Running, Statistics, Travel, University life with tags Benidorm, climatosceptic, computer-simulated model, ISBA conference, optimisation, Valencia meeting on June 5, 2010 by xi'an
Last morning, I attended the talks of Michael Goldstein and Herbie Lee, which were very interesting from very different perspectives. Michael talked about computer models, like the climate models that have been so much attacked recently for being “unrealistic”. The difficulty is obviously in dealing with the fact that the model is incorrect, what Michael calls external uncertainty. As statisticians, we are trained to deal with internal uncertainties, i.e. those conditional on the model. Michael did not propose a generic solution to this difficult problem, but he presented a series of principles towards this goal and his paper in the proceeedings (I have not [yet] read) contains examples of conducting this assessment. (I am not sure building a [statistical] model on top of the current [physical] models stands a chance to convince climato-skeptics, but this is interesting nonetheless.) Herbie addressed a completely different problem, namely the maximisation of a function under constraints when the constraints are partly unknown. (Think of a set whose boundaries are not precisely known.) This was a problem new to me and I plan to read the paper asap, as the design perspective added to the maximisation per se is made in order to decide about the worth of making new [costly] evaluations of the function to maximise.
Otherwise, the morning was spent in a fruitless pursuit of a wireless connection in the hotel where the conference takes place, as so many people were trying to connect at the same time! I eventually resolved the issue by crossing the road to an internet café and renting an ethernet cable for one hour. The hotel is unsurprisingly the soulless and unhelpful place I expected and I do not find any appeal in the high rise landscape constituting the neighbourhood. There is however a small track in the bush nearby that makes for a good running place in the early morning. (Finding a cliff that is both bolted and in the shade is going to prove a challenge!)
Le Monde rank test
Posted in R, Statistics with tags climate change, climatosceptic, correlation, global warming, Le Monde, puzzle, R, Robin Ryder, Spearman rank test on April 5, 2010 by xi'anIn the puzzle found in Le Monde of this weekend, the mathematical object behind the silly story is defined as a pseudo-Spearman rank correlation test statistic,
where the difference between the ranks of the paired random variables 
perm=sample(1:20) saple[t]=sum(abs(perm[1:10]-perm[11:20]))
When regressing the mean of this statistic 
![\mathbb{E} [\mathfrak{M}_n] \approx 0.1681 n^2 - 0.3769 n + 11.1921](https://s0.wp.com/latex.php?latex=%5Cmathbb%7BE%7D+%5B%5Cmathfrak%7BM%7D_n%5D+%5Capprox+0.1681+n%5E2+-+0.3769+n+%2B+11.1921&bg=000000&fg=B0B0B0&s=0&c=20201002)
which does not translate into a nice polynomial in
Another interesting probabilistic/combinatorial problem issued from an earlier Le Monde puzzle: given an urn with 
Ps- The same math tribune in Le Monde coincidently advertises a book, Le Mythe Climatique, by Benoît Rittaud that adresses … climate change issues and the “statistical mistakes made by climatologists”. The interesting point (if any) is that Benoît Rittaud is a “mathematician not a statistician”, with a few papers in ergodic theory, but this advocated climatoskeptic nonetheless criticises the use of both statistical and simulation tools in climate modeling. (“Simulation has only been around for a few dozen years, a very short span in the history of sciences. The climate debate may be an opportunity to reassess the role of simulation in the scientific process.”)
