statistics

R exam

January 30, 2011 | xi'an

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 ... [Read more...]

R programming books (updated)

January 28, 2011 | csgillespie

In a recent post, I asked for suggestions for introductory R computing books. In particular, I was looking for books that: Assume no prior knowledge of programming. Assume very little knowledge of statistics. For example, no regression. Are cheap, since they are for undergraduate students. Some of my cons aren’... [Read more...]

ABC model choice not to be trusted [2]

January 27, 2011 | xi'an

As we were completing our arXiv summary about ABC model choice, we were helpfully pointed to a recent CRiSM tech. report by X. Didelot, R. Everitt, A. Johansen and D. Lawson on  Likelihood-free estimation of model evidence. This paper is quite related to our study of the performances of the ...
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ABC model choice not to be trusted

January 26, 2011 | xi'an

This may sound like a paradoxical title given my recent production in this area of ABC approximations, especially after the disputes with Alan Templeton, but I have come to the conclusion that ABC approximations to the Bayes factor are not to be trusted. When working one afternoon in Park City ...
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CPU and GPU trends over time

January 25, 2011 | csgillespie

GPUs seem to be all the rage these days. At the last Bayesian Valencia meeting, Chris Holmes gave a nice talk on how GPUs could be leveraged for statistical computing. Recently Christian Robert arXived a paper with parallel computing firmly in mind. In two weeks time I’m giving an ...
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Estimate Probability and Quantile

January 25, 2011 | R on Guangchuang Yu

Simple root finding and one dimensional integrals algorithms were implemented in previous posts. These algorithms can be used to estimate the cumulative probabilities and quantiles. Here, take normal distribution as an example. Read More: 281 Words Totally [Read more...]

Inconsistencies in Bayesian Models of Decision-Making

January 20, 2011 | John Myles White

But modeling devices that make sense for an unbiased decisionmaker may not make sense for a biased one. For example, why would individuals have priors and posteriors if they are destined to apply Bayes’ law incorrectly?1 A question I often ask myself. Wolfgang Pesendorfer : Behavioral Economics Comes of Age: A ... [Read more...]

Trip to Lyon

January 20, 2011 | xi'an

This was my first trip to Lyon in about… 35 years, I think, but I did not have much time to tour the city! My original plan was to go climbing with Ivan near La Meije right after the talk, but our respective knees were hurting for the past week at ...
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The ultimate exam excuse…

January 19, 2011 | xi'an

A few days after my R exam (available in French here), I received this email from the department secretary: Pour information cet étudiant est venu me trouver jeudi soir, catastrophé car il venait de constater que son stylo “PILOT Frixion”, stylo semble-t-il recommandé par certains enseignants, ne se contentait pas ... [Read more...]

Séminaire à Lyon

January 17, 2011 | xi'an

Next week, I am going to Lyon to give a seminar in Université Lyon I. I will talk about the recent Rao-Blackwellisation papers we wrote, hopefully managing to make sense with both statisticians and probabilists, unlike in recent talks of mine in probability seminars… The slides are close to those ...
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Introducing Monte Carlo Methods with R [precision]

January 17, 2011 | xi'an

Doug Rivers, professor of Political Sciences in Stanford, kindly sent me this email yesterday night: The 2nd displayed equation in section 2.1.2 on p. 44 is garbled (it might be interpreted as saying that U and X have the same distribution). I think you intended: And indeed we should have stated the ...
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Méthodes de Monte-Carlo avec R [out]

January 17, 2011 | xi'an

The translation of the book Introducing Monte Carlo Methods with R is now published and out! I have received five copies in the mail yesterday, although it was not produced in time for my R class students to get it before the exam today. The book is still indicated on ...
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Missing reference in Monte Carlo Statistical Methods

January 15, 2011 | xi'an

A few days ago, Peng Yu sent me this email Dear Prof. Robert, The citation Edwards and Sokal (1988) appears on page 326 of your book MCSM2. However, I don’t find in in the Reference section (it would have appear on page 601 if it is in the reference section). I don’...
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A lightweight object browser for R

January 15, 2011 | Luke Miller

Get access to a simple object browser in R so that you can see what variables, data frames, model objects and other junk you have in memory currently. If you don't want to install a full-fledged integrated development environment, this option may be fo... [Read more...]

CosmoPMC released

January 12, 2011 | xi'an

Martin Kilbinger, an astronomer (cosmologist) with whom we had worked on population Monte Carlo for cosmological inference [during the ANR-05-BLAN-0283- 04 ANR ECOSSTAT grant], has made the PMC C codes available on the CosmoPMC webpage. He has also written a CosmoPMC manual that is now available from arXiv. And ...
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Random variable generation (Pt 3 of 3)

January 12, 2011 | csgillespie

Ratio-of-uniforms This post is based on chapter 1.4.3 of Advanced Markov Chain Monte Carlo.  Previous posts on this book can be found via the  AMCMC tag. The ratio-of-uniforms was initially developed by Kinderman and Monahan (1977) and can be used for generating random numbers from many standard distributions. Essentially we transform the ... [Read more...]

Two short Bayesian courses in South’pton

January 12, 2011 | xi'an

An announcement for two short-courses on Introduction to  Bayesian Analysis and MCMC, and Hierarchical Modelling of Spatial and Temporal Data by Alan Gelfand (Duke University, USA) and Sujit Sahu (University of Southampton, UK), are to take place in Southampton on June 7-10, this year. Course 1: Introduction to Bayesian Analysis and ... [Read more...]

Le Monde puzzle [1]

January 10, 2011 | xi'an

Following the presentation of the first Le Monde puzzle of the year, I tried a simulated annealing solution on an early morning in my hotel room. Here is the R code, which is unfortunately too rudimentary and too slow to be able to tackle n=1000. #minimise \sum_{i=1}^I x_... [Read more...]
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