Our "arm" package in R requires Doug Bates's "lme4" which fits multilevel models. lme4 is currently having some problems on the Mac. But installation on the Mac can be done; it just takes a bit of work. I have two... [Read more...]

Mandelbrot on taxonomy (from 1955; the first publication about fractals that I know of): Searching for Mandelbrot on the blog led me to Akaike, who also recently passed away and also did interesting early work on self-similar stochastic proces... [Read more...]

Cyrus writes: I [Cyrus] was teaching a class on multilevel modeling, and we were playing around with different method to fit a random effects logit model with 2 random intercepts---one corresponding to "family" and another corresponding to "co... [Read more...]

John Kastellec, Jeff Lax, and Justin Phillips write: Do senators respond to the preferences of their states' median voters or only to the preferences of their co-partisans? We [Kastellec et al.] study responsiveness using roll call votes on te... [Read more...]

Patricia and I have cleaned up some of the R and Bugs code and collected the data for almost all the examples in ARM. See here for links to zip files with the code and data.... [Read more...]

As part of our Red State, Blue State research, we developed statistical tools for estimating public opinion among subsets of the population. Recently Yu-Sung Su, Yair Ghitza, and I applied these methods to see where school vouchers are more or... [Read more...]

David Afshartous writes, What is the difference between sim() and mcsamp(), if any? If there is a difference, what should I expect in terms of difference in results? My reply:... [Read more...]

Yu-Sung writes,... [Read more...]

Aleks pointed me to this site by Alexander Genkin, David D. Lewis, and David Madigan that has a program for Bayesian logistic regression. It appears to allow some hierarchical modeling and can fit very large datasets. I haven't tried it... ... [Read more...]