each year ending in a two or a seven, census bureau employees stow away their eponymous decennial population count to focus on the economic census. and when charged with gauging the health of the american economy, who better to survey than busine...

each year ending in a two or a seven, census bureau employees stow away their eponymous decennial population count to focus on the economic census. and when charged with gauging the health of the american economy, who better to survey than busine...

The Metropolis algorithm, and its generalization (Metropolis-Hastings algorithm) provide elegant methods for obtaining sequences of random samples from complex probability distributions. When I first read about modern MCMC methods, I had trouble visualizing the convergence of Markov chains in higher dimensional cases. So, I thought I might put together a visualization in a two-dimensional case. I’ll use...

While coding ensemble methods in data mining with R, e.g. bagging, we often need to generate many data and models objects with sequential names. Below is a quick example how to use assign() function to generate many prediction objects on the fly and then retrieve these predictions with mget() to do the model averaging.

This morning, Benoit sent me an email, about an exercise he found in an econometric textbook, about linear regression. Consider the following dataset, Here, variable X denotes the income, and Y the expenses. The goal was to fit a linear regression (actually, in the email, it was mentioned that we should try to fit an heteroscedastic model, but let...

Vectors are at the heart of R and represent a true convenience. Moreover, vectors are essential for good performance especially when your are working with lots of data. We’ll explore these concepts in this posting. As a motivational example let’s generate a sequence of data from -3 to 3. We’ll also use each point as