Archive for Marseille

climbing encounters

Posted in Mountains, pictures, Travel with tags , , , , , , , , , , , , on August 28, 2020 by xi'an

A nice if easy climbing morn on Éperon de Bouchier (à ne pas confondre avec Crochet de Boucher!) a week ago with a local guide, François, who happened to be a formidable character (even conditioning on him being guide). He left school at 14 to become a car mechanic, join the French Navy at 16, caught tuberculosis on a Navy basis, was sent to the Alps for recovery, caught a fatal and definite mountain attraction while there, got training supported by the Navy for an higher mechanic degree, took qualification courses to become a French mountain guide, started being interested in learning techniques and abilities through his training ski schools, experimented new teaching methods with kids from the Marseille suburbs,  eventually joined a Master in biomechanics and ergonomy at Orsay and ended up with a thesis on the topic, worked with French ski federation and a French ski brand, and is still guiding, training and researching despite having passed the retirement age! A wonderful chance encounter, with the facility of the route making chatting not an issue. (Except that some puritan ayatollah had recently removed most of the bolts, which did not make things harder in the end but exhibited an absurd degree of self-righteousness on a route that easy…)

And then an even more rewarding climb today with another local guide, Cathy, who gave me a great and profitable climbing lesson for over three hours, allowing me to reach a higher climbing level than I had previously achieved on an outside route. With a high degree of pedagogy and support. I ended up fairly tired, but exhilaratedly so!

souvenirs de Luminy

Posted in Books, Kids, pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , , on July 6, 2020 by xi'an

against method

Posted in Books, Statistics, University life with tags , , , , , , , , , 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 , , , , , on September 15, 2019 by xi'an

Today 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 , , , , , , , , , , , on May 17, 2019 by xi'an