Archive for the Wines Category
Above is the solution produced by a team at the University of Waterloo to the travelling salesman problem of linking all pubs in the UK (which includes pubs in Northern Ireland as well as some Scottish islands—even though I doubt there is no pub at all on the Island of Skye! They also missed a lot of pubs in Glasgow! And worst gaffe of all, they did not include the Clachaigh Inn, probably the best pub on Earth…). This path links over 24 thousand pubs, which is less than the largest travelling salesman problem solved at the current time, except that this case used the exact distances provided by Google maps. Of course, it would somehow make more sense to increase the distances by random amounts as the pub visits increase, unless the visitor sticks to tonic. Or tea.
Tomorrow I am off to Venezia for three days, attending the ESOBE 2016 workshop, where ESOBE stands for European Seminar on Bayesian Econometrics. This year it is indeed taking place in Venezia, Università Ca’ Foscari, in this beautiful building on the Gran Canale, and I have been invited to give a talk. Excited to get back to this unique place, hoping the high water will not be too high to prevent getting around (at random as usual).
This afternoon, I was part of a jury of an astrostatistics thesis, where the astronomy part was about binary objects in the Solar System, and the statistics part about detecting patterns in those objects, unsurprisingly. The first part was highly classical using several non-parametric tests like Kolmogorov-Smirnov to test whether those binary objects were different from single objects. While the p-values were very tiny, I felt these values were over-interpreted in the thesis, because the sample size of N=30 leads to some scepticism about numerical quantities like 0.0008. While I do not want to sound pushing for Bayesian solutions in every setting, this case is a good illustration of the nefarious power of p-values, which are almost always taken at face value, i.e., where 0.008 is understood in terms of the null hypothesis and not in terms of the observed realisation of the p-value. Even within a frequentist framework, the distribution of this p-value should be evaluated or estimated one way or another, as there is no reason to believe it is anywhere near a Uniform(0,1) distribution.The second part of the thesis was about the estimation of some parameters of the laws of the orbits of those dual objects and the point of interest for me was the purely mechanical construction of a likelihood function that was an exponential transform of a sum of residuals, made of squared differences between the observations and their expectations. Or a power of such differences. This was called the “statistical model” in the thesis and I presume in part of the astrostats literature. This reminded me of the first meeting I had with my colleagues from Besançon, where they could not use such mechanical versions because of intractable expectations and used instead simulations from their physical model, literally reinventing ABC. This resolution had the same feeling, closer to indirect inference than regular inference, although it took me half the defence to realise it.
The defence actually took part in the beautiful historical Perrault’s building of Observatoire de Paris, in downtown Paris, where Cassini, Arago and Le Verrier once ruled! In the council room under paintings of major French astronomers, including Laplace himself, looking quite smug in his academician costume. The building is built around the Paris Zero Meridian (which got dethroned in 1911 by the Greenwich Zero Meridian, which I contemplated as a kid since my childhood church had the Greenwich drawn on the nave stones). The customary “pot” after the thesis and its validation by the jury was in the less historical cafeteria of the Observatoire, but it included a jazz big band, which made this thesis defence quite unique in many ways!
Today, I went to Milano for 13 hours to give a seminar at l’Università Bocconi. Where I thus gave a talk on Testing via mixtures (using the same slides as at ISBA last Spring). It was the first time I was in Milano (and thus at Bocconi) for more than a transfer to MCMski or to Pavia and it was great to walk through the city. And of course to meet and share with many friends there. While I glimpsed the end of the sunrise on the Italian Alps (near Monte Rosa?!), I was too late on my way back for the sunset.
And yet another Argentan half-marathon! Which started this blog, so to speak, 8 years ago… Although I could not repeat my feat at the San Francisco half-marathon, as I had lost my high altitude benefits, I managed well enough, with a good overall time of 1:23:28 and a second place in the V2 category, once again. I gained more than one minute from last year time, despite a strong face wind and thanks to sticking to a small group of younger runners. This is one of my best times since the start of the blog in 2008, so I am clearly very happy with the result. And plan to celebrate tonight with a top Montpellier wine!