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Nina Zumel and I ( John Mount ) have been working very hard on producing an exciting new book called “Practical Data Science with R.” The book has now entered Manning Early Access Program (MEAP) which allows you to subscribe to chapters as they become available and give us feedback before the ... [Read more...]

Torturing portfolios to give different volatilities between a factor model and Ledoit-Wolf shrinkage. Previously There have been posts on: “What the hell is a variance matrix?” factor models Ledoit-Wolf shrinkage Question Two of the several ways to produce an estimate of the variance matrix of asset returns is a statistical ... [Read more...]

This question was posed on crossvalidated.com: I have a monthly time series (for 2009–2012 non-stationary, with seasonality). I can use ARIMA (or ETS) to obtain point and interval forecasts for each month of 2013, but I am interested in forecasting the total for the whole year, including prediction intervals. Is there ... [Read more...]

When dealing with survey data in particular, social scientists are often wanting to produce proportions from the data, and associated confidence intervals. The prop.test command in R can be used to generate the desired results. When dealing with small ... [Read more...]

This week-end, I wrote a post since I had some trouble to generate a sample random sample with R, to reproduce one obtained by a co-author, with SAS (generated using Fishman and Moore (1982) used in function RANUNI). I was lucky since another contributor for that book, Christrophe Dutang, got the ... [Read more...]

The community team at Revolution Analytics has just updated this list of resources to learn about R on the Web. Included is this list of the top 3 resources for absolute beginners getting started with R: An Introduction to R – The free, “official” CRAN R Manual Try R – a short course ... [Read more...]

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Some doctors receive more malpractice reports than others. Just how unequal is the distribution of malpractice reports? The post 1.5 percent of doctors, a quarter of malpratice reports appeared first on Decision Science News. [Read more...]

# The SIR Model (susceptible, infected, and recovered) model is a common and useful tool in epidemiological modelling.# In this post and in future posts I hope to explore how this basic model can be enriched by including different population group... [Read more...]

Recently I wrote a blogpost showing the implementation of a simple bubble sort algorithm in pure R code. The downside of that implementation was that is was awfully slow. And by slow, I mean really slow, as in “a 100… See more › [Read more...]

This post is minimalistic. Consider this: Now let's have look at what's inside x: But is it really true? Here you go. A colleague of mine was once ruined by this for an entire day before we realized what was…Read more → [Read more...]

I recently updated my plots of the data analysis tools used in academia in my ongoing article, The Popularity of Data Analysis Software. I repeat those here and update my previous forecast of data analysis software usage. Learning to use … Continue reading → [Read more...]

I've been looking at this article for a new tree-based method. It uses other classification methods (e.g. LDA) to find a single variable use in the split and builds a tree in that manner. The subtleties of the model are: The model does not prune but ... [Read more...]

Summary: Two new measures of tree topology are introduced: temporal clustering (TC), and staircase-ness. Several other existing statistics are also implemented for the purpose of comparison: Aldous's graphical test and likelihood test to decide if a tree fits the Yule … Continue reading → [Read more...]

Which function rbinds dataframes together fastest?First competitor: classic rbind in a for loop over a list of dataframesSecond competitor: do.call("rbind", )Third competitor: rbind.fill() f... [Read more...]

In this blogpost, I want to dive deeper into the explanation of the relationship between Frequency and Recency of Visits with the Conversion Rate and Average Order Value. I have used the RGA package for data extraction and Dr. Hadley Wickham’s ggplot2 package to achieve the visualizations. Here’s ... [Read more...]

Over the last year I worked with two colleagues of mine on the subject of inflation and claims inflation in particular. I didn't expect it to be such a challenging topic, but we ended up with more questions than answers. The key question and biggest ch... [Read more...]

Conrad rolled up a new Armadillo release 3.820 (following two minor fix release in the 0.3.810 series of which we packaged the one that was relevant for us). This new version is now out in a release 0.3.820 of RcppArmadillo which is already on CRAN a... [Read more...]

Guy Freeman writes: I thought you’d all like to know that Stan was used and referenced in a peer-reviewed Rapid Communications paper on influenza. Thank you for this excellent modelling language and sampler, which made it possible to carry out this work quickly! I haven’t actually read the ... [Read more...]