I've been working on this for quite some time (see here for a little background), so I'm pleased that it looks close to done at least as far as the core algorithm. It uses global variables for now, and I'm sure there are a couple of other bugs lurking, but ... [Read more...]

Recently (2008) the European Space Agency produced GlobCover (ESA GlobCover Project, led by MEDIAS-France), the highest resolution (300m) global land cover map to date. GlobCover uses 21 primary land cover classes and many more sub-classes. Land cover classification (LCC) schemes divide the earth into biomes. Biomes are the simplest way to classify ... [Read more...]

In order to move some of my personal interests along, I have been trying to implement the methodology found in Berry and Berry's article Accounting for Multiplicities in Assessing Drug Safety. This methodology uses the MedDRA hierarchy to improve the p... [Read more...]

blotter is an R package that tracks the P&L of your trading systems (or simulations), even if your portfolio spans many security types and/or currencies. This post uses blotter to track a simple two-ETF trading system. The contents of this post b... [Read more...]

Prior to conducting an experiment researchers will often undertake power calculations to determine the sample size required in their work to detect a meaningful scientific effect with sufficient power. In R there are functions to calculate either a minimum sample size for a specific power for a test or the ... [Read more...]

Estimating a proportion at first looks elementary. Hail to aymptotics, right? Well, initially it might seem efficient to iuse the fact that . In other words the classical confidence interval relies on the inversion of Wald’s test. A function to ease the computation is the following (not really needed!). waldci [Read more...]

Just add a third column with link strength to the association matrix plotCophylo2 [Read more...]

My new R package, swfDevice, is getting close to its first release. This package enables native R graphics output as swf (flash) files. It also as the ability to create animations with player controls. The main project page is here and the results of the test suite are here. Here ... [Read more...]

A colleague wanted to extract the median value from a survival analysis object, which turned out to be a pain as the value is not stored in the object, but calculated on the fly by a print method. __ library(survival)__ fit __ survfit(fit)Call: survfit(formula = fit)records n.max ... [Read more...]

I recently wrote a review of Understanding psychology as a science: an introduction to scientific and statistical inference by Zoltan Dienes (2008). Dienes' book covers Neyman-Pearson null hypothesis significance testing, Bayesian inference and the lik... [Read more...]

Theresa Scott, instructor of the previously mentioned R workshop and weekly R clinic, is giving a lecture entitled "Reproducible Research with R, LaTeX, & Sweave" in MRB III, room 1220, this Wednesday 11/18 at 1:30.  You can see more details about the lecture here. Looks like her slides as well as much more introductory ... [Read more...]

Lately, David Smith from REvolution Computing set out to challenge the R community with the reprocuction of a beautiful choropleth map (= multiple regions map/thematic map) on US unemployment rates he had seen on the Flowing Data blog. Here you can find the impressing results. Being a fan of beautiful ... [Read more...]

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Introduction As promised on Thursday, here’s my second pass at a statistical analysis of Canabalt scores. There are some useful results I’ll present right at the start, and then there are some results that are more or less worthless, except that working through my own mistakes helped me ... [Read more...]

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At the office today, I got into a discussion with two of my fellow graduate students about the distribution of scores you can get while playing Canabalt. Because (1) the layout of the levels in the game is fully randomized and (2) the difficulty of certain actions (specifically jumping through windows) is ... [Read more...]

The trellis graphics approach was pioneered by various statistical researchers and the ideas are used extensively in the book “Visualizing Data” by William Cleveland. There are various resources on the website for trellis graphics including S code for creating the majority of the graphs that appear in the book. Inspired ... [Read more...]

Mark Heckmann writes:In your paper "Using Sweave with Lyx" (great work bty) you pointed out that one can see the sweave error code when processing when starting lyx from the terminal. I just changed from Windows to Mac so that's new for me. Could you s... [Read more...]

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