## Archive for Marseille

## souvenirs de Luminy

Posted in Books, Kids, pictures, Statistics, Travel, University life with tags amazon associates, applied Bayesian analysis, Bayesian data analysis, case studies, CIRM, Jean Morlet Chair, Kerrie Mengersen, Lecture Notes in Mathematics, Luminy, Marseille, Pierre Pudlo, Société Mathématique de France, Springer-Verlag, Université Aix Marseille on July 6, 2020 by xi'an## against method

Posted in Books, Statistics, University life with tags Against Method, clinical trials, coronavirus epidemics, COVID-19, drugs, hydroxychloroquine sulfate, Marseille, Mediterranean Sea, Paul Feyerabend, placebo effect on March 29, 2020 by xi'an**A** vitriolic tribune in Le Monde this weekend by the microbologist Didier Raoult, head of the Institut Hospitalo-Universitaire Méditerranée Marseille, campaining for the immediate use of the hydroxychloroquine sulfate drug for coronavirus patients. Arguing that the major emergency of the coronavirus pandemic calls for this use without waiting for confirmation from clinical trials, without controlled comparison with other drugs or a placebo. Solely a study of patients being administered the drug, outside the usual practice of clinical trials.

“Enfin, l’envahissement des méthodologistes amène à avoir des reflexions purement mathématiques.”[At last, the invasion of methodologists leads to purely mathematical reasonings.]

“Ce modèle, qui a nourri une quantité de méthodologistes, est devenu une dictature morale.”[This model, which has fed quantity of methodologists, has become a moral dictatorship.]

“…il faut nous débarasser des mathématiciens, des metéorologistes[sic]dans ce domaine.”[we must get rid of mathematicians and meteorologists in this domain]

“…conseil scientifique dans lequel on trouvait deux modélisateurs de l’avenir (qui pour moi représentent l’équivalent de l’astrologie), des maniaques de la méthodologie. Les médecins confrontés au problème du soin représentaient une minorité qui n’avait pas nécessairement l’habitude de s’exprimer et qui se trouvait noyée par cet habillage pseudo-scientifique.”[…scientific committee including two modelisators of the future (equivalent in my opinion to astrologers), manics of methodology. Physicians facing treatment problems were a minority not necessarily used to intervene, overwhelmed by this pseudo-scientific babbling.]

Obviously I have no expertise in drug development or even in epidemiology, but the name-calling tone of this tribune, as illustrated by the above quotes, is appalling and populist, more in the spirit of Trump than of a rational search for scientific evidence. On the opposite, the arguments therein are a-scientific and reject the use of mathematical and statistical methodology for being… mathematical. And resort to name-calling, while not considering the more than philosophical aspect that opting for this drug rather than another one may be reducing survival chances for some groups of patients. *(While the title chosen for this post reflects the title of Raoult’s tribune, with its philosophical pretenses, let me stress that Feyerabend’s book is not mentioned therein and that the article contains no indication that the author relates to Feyerabend’s views.)*

## the three i’s of poverty

Posted in Books, pictures, Statistics, Travel, University life with tags Gibbs sampling, loss function, Marseille, mixture of distributions, thesis defence, three i's of poverty on September 15, 2019 by xi'an**T**oday I made a “quick” (10h door to door!) round trip visit to Marseille (by train) to take part in the PhD thesis defense (committee) of Edwin Fourrier-Nicolaï, which title was *Poverty, inequality and redistribution: an econometric approach*. While this was mainly a thesis in economics, meaning defending some theory on inequalities based on East German data, there were Bayesian components in the thesis that justified (to some extent!) my presence in the jury. Especially around mixture estimation by Gibbs sampling. (On which I started working almost exactly 30 years ago, when I joined Paris 6 and met Gilles Celeux and Jean Diebolt.) One intriguing [for me] question stemmed from this defense, namely the notion of a Bayesian estimation of a *three i’s of poverty* (TIP) curve. The three i’s stand for incidence, intensity, and inequality, as, introduced in Jenkins and Lambert (1997), this curve measure the average income loss from the poverty level for the *100p*% lower incomes, when p varies between 0 and 1. It thus depends on the distribution F of the incomes and when using a mixture distribution its computation requires a numerical cdf inversion to determine the income *p*-th quantile. A related question is thus on how to define a Bayesian estimate of the TIP curve. Using an average over the values of an MCMC sample does not sound absolutely satisfactory since the upper bound in the integral varies for each realisation of the parameter. The use of another estimate would however require a specific loss function, an issue not discussed in the thesis.

## Calanques, calanques [aka 40/40]

Posted in Mountains, pictures, Running, Travel, University life with tags 50/50, Cap Morgiou, competition, concours photo, France, Luminy, Marseille, Mediterranean Sea, morning run, Parc National des Calanques, sunrise, Université Paris Dauphine on May 17, 2019 by xi'an## mare e monti [climbing up Rumpe Cuou]

Posted in Mountains, pictures, Running, Travel with tags CIRM, farniente des oursins, la Koweit, lead climbing, mare e monti, Marseille, massif des Calanques, multipitch, Parc National des Calanques, rock climbing, Rumpe Cuou, Sormiou on December 18, 2018 by xi'an**W**hile at CIRM for Bayes for Good and Big Bayes workshops, I went again climbing with Nicolas, a guide from Cassis. As we had picked a day when the mistral (a local Northeasterner) was high and made climbing unpleasant and freezing, Nicolas picked a domain on the `other’ side, that was completely protected and started from the sea and went up in the sun, the wind only hitting us at the top, after six pitches, most of which I managed to lead.

We proceeded fast enough to get down for a second route, just as pleasant, finishing at the top as the Sun was setting down behind the islands below us. A well-chosen set of levels (5b, 5c) and rock-types like slab for my level and a nice conslusion to three climbing outings within a month. (Note that most pictures of our route are not mine as my camera battery went down before we even started.)