Publications by xi'an
R exam
I spent most of my Saturday perusing R codes to check the answers written by my students to the R exam I gave two weeks ago… The outcome is mostly poor, even though some managed to solve a fair part of the long problem. Except for the few hopeless cases who visibly never wrote a single line of R code before the exam, all students have managed t...
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ABC model choice not to be trusted [3]
On Friday, I received a nice but embarrassing email from Xavier Didelot. He indeed reminded me that I attended the talk he gave at the model choice workshop in Warwick last May, as, unfortunately but rather unsurprisingly giving my short span memory!, I had forgotten about it! Looking at the slides he joined to his email, I indeed remembered atte...
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Le Monde puzzle [#4]
A fairly simple puzzle in this weekend Le Monde magazine: given five points on a line such that their pairwise distances are 1,2,4,…,14,18,20, find the respective positions of the five points over the line and deduce the missing distances. Without loss of generality, we can set the first point at 0 and the fifth point at 20. The three remaining...
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Latent Gaussian Models in Zürich [day 1]
An interesting first day (for me) at the Latent Gaussian Models workshop in Zürich. The workshop is obviously centred at the INLA approach, with Havard Rue giving a short course on Wednesday then a wide ranging tour of the applications and extensions of INLA this afternoon. Thanks to his efforts in making the method completely accessible for man...
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Latent Gaussian Models im Zürich [day 2]
The second day at the Latent Gaussian Models workshop in Zürich was equally interesting. Among the morning talks, let me mention Daniel Bové who gave a talk connected with the hyper-g prior paper he wrote with Leo Held (commented in an earlier post) and the duo of Janine Illian and Daniel Simpson who gave enthusiastic arguments as to why point ...
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Merci taxi!
I am in Montpellier today for a general meeting of our EMILE ANR grant bi-yearly meeting, discussing ABC model choice and new applications of simulation methods in population genetics, including an upgrade of DIYABC into the 2.0 version. (The above is a picture comparing “true” Bayes factors with ABC versions, commented in my Zürich talk las...
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Model weights for model choice
An ‘Og reader. Emmanuel Charpentier, sent me the following email about model choice: I read with great interest your critique of Peter Congdon’s 2006 paper (CSDA, 50(2):346-357) proposing a method of estimation of posterior model probabilities based on improper distributions for parameters not present in the model inder examination, as well ...
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Le Monde puzzle [#5]
Another Sudoku-like puzzle from the weekend edition of Le Monde. The object it starts with is a 9×9 table where each entry is an integer and where neighbours take adjacent values. (Neighbours are defined as north, west, south and east of an entry.) The question is about whether or not it is possible to find a table such that the sum of the 81 en...
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Parallel computation [back]
We have now received reports back from JCGS for our parallel MCMC paper and they all are very nice and supportive! The reviewers essentially all like the Rao-Blackwellisation concept we developed in the paper and ask for additions towards a more concrete feeling for the practical consequences of the method. We should thus be able to manage a revi...
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Another Bernoulli factory
The paper “Exact sampling for intractable probability distributions via a Bernoulli factory” by James Flegal and Radu Herbei got posted on arXiv without me noticing, presumably because it came out just between Larry Brown’s conference in Philadelphia and my skiing vacations! I became aware of it only yesterday and find it quite interesting ...
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