Nicolas Chopin emailed me about the opening of a position of Professor of Statistics at [my alma mater] ENSAE, on the Paris-Saclay campus [and plateau], next to Polytechnique, Telecom, and a bunch of other engineer schools [a.k.a The French MIT!]. The largest concentration of Science majors in France, definitely to be considered for a posiiton in France! Deadline is quite soon, as November 1. [Pardon my French: The pun in the title sort of fizzled out in translation because served on a plate is equivalent to served on a plateau in French.]
Archive for École Polytechnique
a position served on a plate [ENSAE ParisTech, France]
Posted in Kids, pictures, Statistics, Travel, University life with tags academic position, École Polytechnique, ENSAE, France, lost in translation, Paris-Saclay campus, ParisTech, positions, professor of statistics, Saclay, translation on October 6, 2017 by xi'anHamiltonian MC on discrete spaces
Posted in Statistics, Travel, University life with tags École Polytechnique, BNP11, capture-recapture, ergodicity, Hamiltonian Monte Carlo, Jolly-Seber model, Laplace distribution, Montréal, open population on July 3, 2017 by xi'an
Following a lively discussion with Akihiko Nishimura during a BNP11 poster session last Tuesday, I took the opportunity of the flight to Montréal to read through the arXived paper (written jointly with David Dunson and Jianfeng Liu). The issue is thus one of handling discrete valued parameters in Hamiltonian Monte Carlo. The basic “trick” in handling this complexity goes by turning the discrete support via the inclusion of an auxiliary continuous variable whose discretisation is the discrete parameter, hence resembling to some extent the slice sampler. This removes the discreteness blockage but creates another difficulty, namely handling a discontinuous target density. (I idly wonder why the trick cannot be iterated to second or higher order so that to achieve the right amount of smoothness. Of course, the maths behind would be less cool!) The extension of the Hamiltonian to this setting by a convolution is a trick I had not seen since the derivation of the Central Limit Theorem during Neveu’s course at Polytechnique. What I find most exciting in the resolution is the move from a Gaussian momentum to a Laplace momentum, for the reason that I always wondered at alternatives [without trying anything myself!]. The Laplace version is indeed most appropriate here in that it avoids a computation of all discontinuity points and associated values along a trajectory. Since the moves are done component-wise, the method has a Metropolis-within-Gibbs flavour, which actually happens to be a special case. What is also striking is that the approach is both rejection-free and exact, provided ergodicity occurs, which is the case when the stepsize is random.
In addition to this resolution of the discrete parameter problem, the paper presents the further appeal of (re-)running an analysis of the Jolly-Seber capture-recapture model. Where the discrete parameter is the latent number of live animals [or whatever] in the system at any observed time. (Which we cover in Bayesian essentials with R as a neat entry to both dynamic and latent variable models.) I would have liked to see a comparison with the completion approach of Jérôme Dupuis (1995, Biometrika), since I figure the Metropolis version implemented here differs from Jérôme’s. The second example is built on Bissiri et al. (2016) surrogate likelihood (discussed earlier here) and Chopin and Ridgway (2017) catalogue of solutions for not analysing the Pima Indian dataset. (Replaced by another dataset here.)
end of a long era [1982-2017]
Posted in Books, pictures, Running, University life with tags École Polytechnique, badge, boxes, CREST, ENSAE, INSEE, Insee Paris Club, Malakoff, moving, office, Paris, Paris-Saclay campus on May 23, 2017 by xi'an
This afternoon I went to CREST to empty my office there from books and a few papers (like the original manuscript version of Monte Carlo Statistical Methods). This is because the research centre, along with the ENSAE graduate school (my Alma mater), is moving to a new building on the Saclay plateau, next to École Polytechnique. As part of this ambitious migration of engineering schools from downtown Paris to a brand new campus there. Without getting sentimental about this move, it means leaving the INSEE building in Malakoff, on the outskirts of downtown Paris, which has been an enjoyable part of my student and then academic life from 1982 till now. And also leaving the INSEE Paris Club runners! (I am quite uncertain about being as active at the new location, if only because going there by bike is a bit more of a challenge. To be addressed anyway!) And I left behind my accumulation of conference badges (although I should try to recycle them for the incoming BNP 11 in Paris!).
the French MIT? not so fast…
Posted in Kids, pictures, University life with tags École Polytechnique, ENSAE, French politics, French universities, Orsay, Paris-Saclay campus, PSL, Université Paris Dauphine on February 20, 2017 by xi'an
A news report last weekend on Nature webpage about the new science super-campus south of Paris connected with my impressions of the whole endeavour: the annual report from the Court of Auditors estimated that the 5 billion euros invested in this construct were not exactly a clever use of public [French taxpayer] money! This notion to bring a large number of [State] engineer and scientific schools from downtown Paris to the plateau of Saclay, about 25km south-west of Paris, around École Polytechnique, had some appeal, since these were and are prestigious institutions, most with highly selective entry exams, and with similar training programs, now that they have almost completely lost the specialisation that justified their parallel existences! And since a genuine university, Paris 11 Orsay, stood nearby at the bottom of the plateau. Plus, a host of startups and research branches of companies. Hence the concept of a French MIT.
However, as so often the case in Jacobin France, the move has been decided and supported by the State “top-down” rather than by the original institutions themselves. Including a big push by Nicolas Sarkozy in 2010. While the campus can be reached by public transportation like RER, the appeal of living and working on the campus is obviously less appealing to both students and staff than in a listed building in the centre of Paris. Especially when lodging and living infrastructures are yet to be completed. But the main issue is that the fragmentation of those schools, labs and institutes, in terms of leadership, recruiting, research, and leadership, has not been solved by the move, each entity remaining strongly attached to its identity, degree, networks, &tc., and definitely unwilling to merge into a super-university with a more efficient organisation of teaching and research. Which means the overall structure as such is close to invisible at the international level. This is the point raised by the State auditors. And perceived by the State which threatens to cut funding at this late stage!
This is not the only example within French higher educations institutions since most have been forced to merged into incomprehensible super-units under the same financial threat. Like Paris-Dauphine being now part of the PSL (Paris Sciences et Lettres) heterogeneous conglomerate. (I suspect one of the primary reasons for this push by central authorities was to create larger entities towards moving up in the international university rankings, which is absurd for many reasons, from the limited worth of such rankings, to the lag between the creation of a new entity and the appearance on an international university ranking, to the difficulty in ranking researchers from such institutions: in Paris-Dauphine, the address to put on papers is more than a line long, with half a dozen acronyms!)
postdoc on missing data at École Polytechnique
Posted in Kids, pictures, R, Statistics, Travel, University life with tags École Polytechnique, Bayesian inference, CMAP, France, generalized SVD, latent variable models, matrix completion, missing data, Palaiseau, Paris, postdoctoral position, R on November 18, 2016 by xi'an
Julie Josse contacted me for advertising a postdoc position at École Polytechnique, in Palaiseau, south of Paris. “The fellowship is focusing on missing data. Interested graduates should apply as early as possible since the position will be filled when a suitable candidate is found. The Centre for Applied Mathematics (CMAP) is looking for highly motivated individuals able to develop a general multiple imputation method for multivariate continuous and categorical variables and its implementation in the free R software. The successful candidate will be part of research group in the statistical team on missing values. The postdoc will also have excellent opportunities to collaborate with researcher in public health with partners on the analysis of a large register from the Paris Hospital (APHP) to model the decisions and events when severe trauma patients are handled by emergency doctors. Candidates should contact Julie Josse at polytechnique.edu.”
