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...

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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...

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...

Cyrus writes: I 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...

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 study responsiveness using roll call votes on te...

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....

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...

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:...

Yu-Sung writes,...

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... ...