The Cox-Stuart test is defined as a little powerful test (power equal to 0.78), but very robust for the trend analysis. It is therefore applicable to a wide variety of situations, to get an idea of the evolution of values obtained. The proposed method is based on the binomial distribution. In ... [Read more...]

The one-way analysis of variance is a useful technique to verify if the means of more groups are equals. But this analysis may not be very useful for more complex problems. For example, it may be necessary to take into account two factors of variability to determine if the averages ... [Read more...]

Two-allele model has alleles A1 and A2 and genotypes A1A1, A1A2, and A2A2. This model can be fitted using only additive effect (restricted model) or additve+dominance effect. (full model) The later model has one parameter more than the former. I was using this model lately and ... [Read more...]

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So today I compiled 64 bit R 2.91 on Mac OS X   10.5.7 in order to get maximum speed for my analyses. The speed increase I got was 15-25 %, when I ran some tests with matrix calculation and intensive loops. Note that you can also download optimized binaries from  http://r.research.att.... [Read more...]

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This is a really simple code snippet that shows how to get the list of CRAN packages and their titles from the html page html page (toulouse mirror in this example). ... Note that R has the available.packages function, but it does not give th... [Read more...]

Inspired by this post (suggested here by the always useful Revolutions blog), I attempted to plot the position of CRAN mirrors on a map taking advantage of the nice R package RgoogleMaps (check the dependencies!). Below the code: library(XML) # downlo... [Read more...]

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If you have qualitative variable, it is possible to verify the correlation by studying a contingency table R by C, using the Pearson's Chi-squared test.A casino wants to study the correlation between the modes of play and the number of winners by age group, to see if the number ... [Read more...]

Our survey paper on the current state of the art in parallel computing with R, previously mentioned here as a technical report is now out as Vol 31, Issue 1 of the all-electronic Journal of Statistical Software. [Read more...]

pre{ border: 1px solid black; font-family: "Courier New" !important; font-size: xx-small !important; } The parser package has been released to CRAN, the package mainly defines a function parser that is similar to the usual R function parse, w... [Read more...]

This post is motivated by this question on R-help. This is a simple java class that sends files through Rserve using the classes RFileInputStream and RFileOutputStream Then we create a simple file on the client machine: $ cat __ testfile.tx... [Read more...]

I have been to many conferences. Most of them are of Political Science. The common feature of these conferences is that the audience size is always small. If you get 10 audiences in your panel, your must be a big name.My presentation at the useR! 20... [Read more...]

We saw in the previous post, how to study the correlation between variables that follow a Gaussian distribution with the Pearson product-moment correlation coefficient. If it is not possible to assume that the values follow gaussian distributions, we have two non-parametric methods: the Spearman's rho test and Kendall's tau test.... [Read more...]

Version 0.6.6 of Rcpp [ a set of C++ classes making it easier to glue C/C++ code to R ] went off to CRAN and Debian earlier as another small maintenance release. While the diffstat output that will appear in cranberries may look impressive, it ste... [Read more...]

I've started the process of moving the content of this page to the R wiki. The motivation is that the content will become dynamic and updated much more often, people can add their own project, we can have use cases of each gui, tutorials, feature c... [Read more...]

Suppose you want to study whether there is a correlation between 2 sets of data. To do this we compute the Pearson product-moment correlation coefficient, which is a measure of the correlation (linear dependence) between two variables X and Y; then we ... [Read more...]

Since my last attendance of the useR conference in Vienna, Austria, I have always wanted to go back. However, the high registration fee was always the factor that chills me off.This year, I am taking advantage of my last year as the student (the regis... [Read more...]

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