Blog Archives

MCMC convergence assessment

November 27, 2012
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MCMC convergence assessment

Richard Everitt tweetted yesterday about a recent publication in JCGS by Rajib Paul, Steve MacEachern and Mark Berliner on convergence assessment via stratification. (The paper is free-access.) Since this is another clear interest of mine’s, I had a look at the paper in the train to Besançon. (And wrote this post as a result.) The

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Successive Differences of a Randomly-Generated Timeseries

November 25, 2012
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I was wondering about the null distribution of successive differences of random sequences, and decided to do some numerical experiments. I quickly realized that successive differences equates to taking successively higher-order numerical derivatives, ...

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optimising accept-reject

November 20, 2012
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optimising accept-reject

I spotted on R-bloggers a post discussing optimising the efficiency of programming accept-reject algorithms. While it is about SAS programming, and apparently supported by the SAS company, there are two interesting features with this discussion. The first one is about avoiding the dreaded loop in accept-reject algorithms. For instance, taking the case of the truncated-at-one

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R midterms

November 9, 2012
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R midterms

Here are my R midterm exams, version A and version B in English (as students are sitting next to one another in the computer rooms), on simulation methods for my undergrad exploratory statistics course. Nothing particularly exciting or innovative! Dedicated ‘Og‘s readers may spot a few Le Monde puzzles in the lot… Two rather entertaining

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visit to ISU

October 30, 2012
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visit to ISU

  A short visit to ISU but and therefore a busy and proftable day! About ten appointments in Snedecor Hall after a nice morning run, a highly attended Zyskind Lecture, and many interesting discussions all over the day: e.g., I had a great time discussing using null recurrent Markov chains for integral approximations with Krishna

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the large half now

October 28, 2012
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the large half now

The little half puzzle proposed a “dumb’ solution in that players play a minimax strategy. There are 34 starting values less than 100 guaranteeing a sure win to dumb players. If instead the players maximise their choice at each step, the R code looks like this: and there are now 66 (=100-34, indeed!) starting values

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the little half (another Le Monde puzzle)

October 27, 2012
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the little half (another Le Monde puzzle)

I found this Le Monde puzzle of June 16 I had stored and then somehow forgotten with my trips to Japan and Australia: There are n beans in a box, with 98≤n≤102). Two players take at each round either one bean from the box or “the little half” (i.e. the integral part of the half)

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Le Monde puzzle (rainy Sunday!)

October 20, 2012
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Le Monde puzzle (rainy Sunday!)

On October 14, the weekend edition of Le Monde had the following puzzle: consider four boxes that contain all integers between 1 and 9999, in such a way that for any N, N, 2N, 3N, and 4N are in four different boxes. If 1,2,3 and 4 are in boxes labelled 1,2,3 and 4, respectively, in

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R for dummies

October 19, 2012
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R for dummies

Just saw this nice review of R for dummies. And thought after this afternoon class that my students in the simulation course at Paris-Dauphine could clearly benefit from reading it! They in fact had a terrible time simulating a truncated normal distribution by accept-reject. As they could not get the notion of normalising constants… (Yes,

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slides for my simulation course

October 18, 2012
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slides for my simulation course

Similar to last year, I am giving a series of lectures on simulation jointly as a Master course in Paris-Dauphine and as a 3rd year course in ENSAE. The course borrows from both the books Monte Carlo Statistical Methods and from Introduction to Monte Carlo Methods with R, with George Casella. Here are the three

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