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...]

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...]

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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...]

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...]

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Last week, during the workshop on Statistical Methods for Meteorology and Climate Change (here), I discovered how powerful bayesian techniques could be, and that there were more and more bayesian statisticians. So, if I was to fully understand app... [Read more...]

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...]

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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...]

A brief review of Zuur et al.'s book "Mixed Effects Models and Extensions in Ecology with R". [Read more...]

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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...]

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...]

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...]