Blog Archives

Generating a Markov chain vs. computing the transition matrix

May 23, 2013
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Generating a Markov chain vs. computing the transition matrix

A couple of days ago, we had a quick chat on Karl Broman‘s blog, about snakes and ladders (see http://kbroman.wordpress.com/…) with Karl and Corey (see http://bayesianbiologist.com/….), and the use of Markov Chain. I do believe that this application is truly awesome: the example is understandable by anyone, and computations (almost any kind, from what we’ve tried) are easy to perform....

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Playing cards in Vegas?

May 19, 2013
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Playing cards in Vegas?

In a previous post, a few weeks ago, I mentioned that I will be in Las Vegas by the end of July. And I took the opportunity to write a post on roulette(s). Since some colleagues told me I should take some time to play poker there, I guess I have to understand how to play poker… so I...

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From a random generator to a sample function

May 14, 2013
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From a random generator to a sample function

This week-end, I wrote a post since I had some trouble to generate a sample random sample with R, to reproduce one obtained by a co-author, with SAS (generated using Fishman and Moore (1982) used in function RANUNI). I was lucky since another contributor for that book, Christrophe Dutang, got the anwer to the last question I asked: is it...

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Playing cards, with R

May 11, 2013
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Playing cards, with R

In my courses on R, I usually show how to insert a picture as a background for a graph. But it is also to see the picture as an object, and to insert it in a graph everywhere we like to see it, as explained on the awesome blog http://rsnippets.blogspot.ca/…. (in a post published in January 2012). I wanted...

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Reproducibility and randomness

May 11, 2013
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Reproducibility and randomness

With Stéphane Tufféry, we were working this week on a chapter of a book, entitled Statistical Learning in Actuarial Science. The chapter should be based on R functions, and we wanted to reproduce some outputs he previously obtained with SAS. The good thing is that even complex functions (logistic regression, regression trees, etc) produce the same kind of outputs....

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Poisson regression on non-integers

May 7, 2013
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Poisson regression on non-integers

In the course on claims reserving techniques, I did mention the use of Poisson regression, even if incremental payments were not integers. For instance, we did consider incremental triangles > source("http://perso.univ-rennes1.fr/arthur.charpentier/bases.R") > INC=PAID > INC=PAID-PAID > INC 3209 1163 39 17 7 21 3367 1292 37 24 10 NA 3871...

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LaTeX in R graphs

May 3, 2013
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LaTeX in R graphs

A nice post was recently published on the rsnippets blog, about the tikzDevice R package. This package is – indeed – awesome. Even if it has been removed from the CRAN website. Of course, it can be download from the archive folder, on http://cran.r-project.org/…, but also (for a more recent version)  on http://download.r-forge.r-project.org/…. But first, it is necessary to install...

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Animation, from R to LaTeX

May 3, 2013
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Animation, from R to LaTeX

Just a short post, to share some codes used to generate animated graphs, with R. Assume that we would like to illustrate the law of large number, and the convergence of the average value from binomial sample. We can generate samples  using > n=200 > k=1000 > set.seed(1) > X=matrix(sample(0:1,size=n*k,replace=TRUE),n,k) Each row  will be a trajectory of heads and...

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In three months, I’ll be in Vegas (trying to win against the house)

April 20, 2013
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In three months, I’ll be in Vegas (trying to win against the house)

In fact, I’m going there with my family and some friends, including two probabilists (I mean professionals, I am merely an amateur), with this incredible challenge: will I be able to convince  probabilists to go to play at the Casino? Actually, I also want to study them carefully, to understand how we should play optimally. For example, I hope...

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Reserving with negative increments in triangles

April 11, 2013
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Reserving with negative increments in triangles

A few months ago, I did published a post on negative values in triangles, and how to deal with them, when using a Poisson regression (the post was published in French). The idea was to use a translation technique: Fit a model not on ‘s but on , for some , Use that model to make predictions, and then...

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