## postdoc shortage

Posted in Books, pictures, Statistics, Travel, University life with tags , , , , , , , , , on October 4, 2022 by xi'an

An interesting tribune in Nature (30 August) about the difficulty in hiring postdocs… I myself faced this difficulty in the recent years but though it was mostly due to unattractive French salaries and working conditions, or COVID issues (or myself!). Nature mentions politics, economics, ethics, and personal priorities as main reasons for the postdoctoral drought. In Britain, Brexit is definitely a central factor as candidates face enormous bills to secure entry to the United Kingdom (as Hai-Dang Dau, now in Oxford, was explaining to us after his successful PhD defense at ENSAE-CREST this morning). But more globally this may reflect a general exodus from academia towards company jobs, and their much more attractive salaries. Especially in STEM where Amazon and buddies created a new definition of “dream jobs”… Anyway,  I still have a prAirie postdoc position open in Paris Dauphine and the new PariSanté campus provides a great working environment, so feel free to contact me!

## new campus

Posted in pictures, Running, Travel, University life with tags , , , , , , , , , , , , on September 4, 2022 by xi'an

While I am keeping my office at Porte Dauphine, undergoing major renovations (of the 1955 NATO building!), I am now spending most of my time in a more modern campus, called PariSanté, located at Porte de Versailles, with medical research teams and startups. This is where our master MASH will be located. The place is very luminous and despite the close proximity with the Paris beltway (le périf’), quiet (and much quieter than Paris Dauphine). It is also an ecological absurdity, with a huge sunroof that could not be shaded during the heat waves, plastic trees, self-induced lights, and compulsory lifts. On the memory lane, it is a trip back 35 years ago, as it sits across the road from the Balard military compound where I spent most of my military service in 1987 (working on my PhD in a research department).  And it is conveniently located half-way between home and Paris Dauphine, although not skipping the tough hill of Porte de Versailles on the way back..!

## new bike

Posted in Travel, University life with tags , , , , , , on August 28, 2022 by xi'an

My university, Paris Dauphine, has recently introduced some support for its cycling staff as a substitute for the compulsory support for public transportation costs. Meaning reimbursing part of the cost of buying a new bike over two years. After one too many trip to the bike repair shop, I thus started looking for a sturdy enough gravel-like) bike with disk brakes (that did not need changing every three weeks!) to handle the Paris cobbles and saw this Trek Domane on sale at the (same) shop, which I bought when returning from Québec. After a few weeks of using it (solely) between home and campus, never to go shopping or swimming!, I am definitely appreciating the comfort and efficiency of this new bike! Hopefully, this will last over the Fall, despite worsening conditions in weather and traffic!

## master project?

Posted in Books, Kids, Statistics, University life with tags , , , , , , , on July 25, 2022 by xi'an

A potential master project for my students next year inspired by an X validated question: given a Gaussian mixture density

$f(x)\propto\sum_{i=1}^m \omega_i \sigma^{-1}\,\exp\{-(x-\mu_i)^2/2\sigma^2\}$

with m known, the weights summing up to one, and the (prior) information that all means are within (-C,C), derive the parameters of this mixture from a sufficiently large number of evaluations of f. Pay attention to the numerical issues associated with the resolution.  In a second stage, envision this problem from an exponential spline fitting perspective and optimise the approach if feasible.

## efficient measures?

Posted in Books, Statistics, University life with tags , , , , , , , , , on July 24, 2022 by xi'an

When checking the infographics of the week highlighted by Nature, I came across this comparison of France and Germany for the impact of their respective vaccination mandates on health and economics. And then realised this was from a preprint from a Paris Dauphine colleague, Miquel Oliu-Barton (and co-authors). The above graphs compare the impact of governmental measures towards vaccination, short of compulsory vaccination (unfortunately).  Between Germany and France, it appears as if the measures were more effective in the latter. Which may be interpreted as either a consequence of the measures being more coercive in [unruly] France or an illustration of the higher discipline of the German society [despite the government contemplating compulsory vaccination for a while]. As an aside, I am very surprised at the higher death rate in Germany but, beside a larger percentage of people over 65 there and a lower life expectancy, the French curve is interrupted in December 2021. Looking at 2022, the peak was reached at 3.3 cases per day per million people.

Concerning the red counterfactual curves, I did not find much explanation in the preprint, apart from

“Our results are supported by the well-established econometric method of synthetic control.³⁰ We construct counterfactuals for each treated country based on a weighted average of countries that did not implement the COVID certificate and find consistent trajectories for the time period where this method is feasible, i.e., until the end of September 2021.”

and

“constructing counterfactuals ( i.e., by modelling vaccine uptake without this intervention), using innovation diffusion theory.⁶Innovation diffusion theory was introduced to model how new ideas and technologies spread”

which is not particularly helpful without further reading.