I once heard John Chambers (the inventor of the S language, and member of the R Core Group) say, "Show me a programming language no-one complains about, and I'll show you a language no-one uses". The R language has its fair share of complainants, to be sure -- and that's ... [Read more...]

I should state right away that I know almost nothing about queuing theory. That’s one of the reasons I wanted to do some queuing simulations. Another reason: when I’m waiting in line at the bank, I tend to do mental calculations for how long it should take me ... [Read more...]

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In part 3, we ran a logistic model to determine the probability of default of a customer. We also saw the outputs and tried to judge the performance of the model b plotting the ROC curve. Let's try a different approach today. How about a decision tree?... [Read more...]

This is the first post in the series about Asset Allocation, Risk Measures, and Portfolio Construction. I will use simple and naive historical input assumptions for illustration purposes across all posts. In these series I plan to discuss: Maximum Loss, MAD, CVaR, CDaR, Omega Risk Measures 130:30 Long/Short portfolios and ... [Read more...]

In this article, Hans Gilde exposes the clever use of a heatmap hidden in the Bioconductor library. In his example, he describes a way to show different ‘observations’ on subjects, with the concept of time. Financial indices, like the S&P 500 or the Dow Jones indices, are mathematically some kind ... [Read more...]

To me, this post by Christophe Ladroue personifies what data doodlers do.They take a dataset that is of interest to them (In his case, his triathlon results) and then they manipulate the numbers to see what insights can be drawn. Most bloggers only sho... [Read more...]

The two translators of our book in Japanese, Kazue & Motohiro Ishida, contacted me about some R code mistakes in the book. The translation is nearly done and they checked every piece of code in the book, an endeavour for which I am very grateful! Here are the two issues they ... [Read more...]

Impressive. You are not alone! [Read more...]

With data from the USDA on certified organic farms for 2008.  I created a map using the Geo Map function from the googleVis API package available in R.  I’ve copied and pasted the image below as WordPress.com sites don’t support … Continue reading → [Read more...]

If you missed last week's webinar from Bob Muenchen, "Introduction to R for SAS and SPSS users", you missed a great overview of the R Project and how it compares to commercial statistical software. Bob's slides are below, and you can download the slides and replay from the Revolution Analytics ... [Read more...]

Check out this talk by John Rauser of AMZN at the 2011 Strata Conf. It is an excellent intro to the field. [Read more...]

Some scholars suggest that multiply imputing an outcome variable is incorrect. I use intuition and simulation to argue that multiply imputing outcomes can drastically improve estimates, even in the case of non-ignorable missingness. Continue reading &#... [Read more...]

Every year there is at least a couple of occasions when I have to simulate multivariate data that follow a given covariance matrix. For example, let’s say that we want to create an example of the effect of collinearity when … Continue reading → [Read more...]

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I normally work with full numerical data, not categorical data. R, when using read.csv() seems to recognize such categories and marks the column as to have factor levels. This is useful indeed. However, I wanted to make a PCA biplot on this data, so wa... [Read more...]

Update 10/11/2011: There’s a good discussion on RedditUpdate 10/12/2011: Note manipulate package and highlight data.table packageThe R statistical computing platform is a rising star that’s been gaining popularity and attention, but it gets no respect in the hood. It’s telling that a popular guide to R is called ... [Read more...]

Karl Broman writes: Barry Rowlingson gave an interesting talk at UseR 2011, “Why R-help must die!” He suggested the Q-and-A type sites Stack Overflow (on programming) and Cross Validated (on statistics), both part of Stack Exchange. I haven’t used R-help recently but I do occasionally send people there. Just to ... [Read more...]

Yesterday I launched my first question at Stackoverflow and apparently did a lot of things wrong as I managed to get my question closed wihtin hours http://stackoverflow.com/questions/7728462/identify-records-in-data-frame-a-not-contained-in-data-frame-b I had collected 9 different solutions to the problem and made the mistake to put it all within the original ... [Read more...]