The Holt-Winters method is a popular and effective approach to forecasting seasonal time series. But different implementations will give different forecasts, depending on how the method is initialized and how the smoothing parameters are selected. In this post I will discuss various initialization methods. Suppose the time series is denoted ... [Read more...]

An interesting note was arXived a few days ago by Madeleine Thompson and Radford Neal. Beside the nice touch of mixing crumbs and slices, the neat idea is to have multiple-try proposals for simulating within a slice and to decrease the dimension of the simulation space at each try. This ... [Read more...]

This is a clip from the forthcoming BBC4 program, The Joy of Stats: The clip shows Hans Rosling (who we've profiled here before), plotting life expectancy versus income for various countries, and animating over time. The clip amply demonstrates that with the right presentation and story, even the simplest of ... [Read more...]

John Chambers, one of the creators of R's predecessor S and a current member of the R Core Group, gave a seminar at Stanford last week titled "R, other languages and object-oriented programming". Unfortunately, I was away for the Thanksgiving break and couldn't make it myself, but John has kindly ... [Read more...]

Last course will be uploaded soon (the links will be here and there). The R code considered is given below. First, we had to work a little bit on the datasets, tabB=read.table("http://perso.univ-rennes1.fr/arthur.charpentier/tabB.csv", sep=";",head... [Read more...]

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The book Random effects and latent variable model selection, edited by David Dunson in 2008 as a Springer Lecture Note. contains several chapters dealing with evidence approximation in mixed effect models. (Incidentally, I would be interested in the story behind the  Lecture Note as I found no explanation in the backcover ... [Read more...]

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As I mentioned in a recent post, I’ve just received a copy of Advanced Markov Chain Monte Carlo Methods. Chapter 1.4 in the book (very quickly) covers random variable generation. Inverse CDF Method A standard algorithm for generating random numbers is the inverse cdf method. The continuous version of the ... [Read more...]

I've pushed a new version of the parser package to CRAN. This is the first release that depends on Rcpp, which allowed me to reduce the code size and increase its maintainability. This also features a faster version of nlines, a function that r... [Read more...]

Rcpp 0.8.9 was pushed to CRAN recently. Apart from minor bug fixes, this release concentrates on modules, with lots of new features to expose C++ functions and classes through R reference classes. The Rcpp-modules vignette has all the details, a... [Read more...]

An obvious omission in my previous post on Great-circle distance calculations in R was a lack of discussion on the computational efficiency of the various methods, and in particular comparing different implementations of the same method. One of the comments … Continue reading → [Read more...]

The LaTeX typesetting is used to create professional looking documents on a home computer. It may have a steeper learning curve than using a Word Processor, but this initial effort will often pay off reasonably quickly. The system is almost a necessity for anyone writing documents with a large amount ... [Read more...]

I’ve just received my copy of Advanced Markov Chain Monte Carlo Methods, by Liang, Liu, & Carroll. Although my PhD didn’t really involve any Bayesian methodology (and my undergrad was devoid of any Bayesian influence), I’ve found that the sort of problems I’m now tackling in systems ... [Read more...]

Conrad Sanderson released version 1.0.0 of Armadillo, his templated C++ library for linear algebra, earlier this week. So congratulations to Conrad on reaching 1.0.0! I folded his version 1.0.0 into a new release 0.2.10 of RcppArmadillo, our Rcpp-base... [Read more...]

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In connection with Le Monde puzzle #46, I eventually managed to write an R program that generates graphs with a given number n of nodes and a given number k of edges leaving each of those nodes. (My early attempt was simply too myopic to achieve any level of success when ... [Read more...]

Kaggle, the predictive-analytics competition site, has analyzed the preferences of the 2,500 data scientists who participate in its competitions, and R was the most-preferred software of the competitors at 22.5%. The next-nearest alternative was Matlab, at 16%. On a related note, the premier of the Australian state of New South Wales has just ... [Read more...]

Just read a funny but much to the point blog entry on the difficulties of teaching proper programming skills to first year students! I will certainly make use of the style file as grading 180 exams is indeed a recurrent nightmare… Filed under: R,... [Read more...]