Saturday, July 17, 2010

Bayes Election Prediction R Code, Gelman, Tokdar

Attached is the R code that calculates a prediction for 1992 presidential election based on methods found in Andrew Gelman's Bayesian Data Analysis book. The R code itself is written by Dr. Surya Tokdar; however the links at CMU that housed this and his other lecture related materials were all gone. I salvaged what I could from Google cache, removed all plotting, graphics related portions of the code, leaving only MCMC Gibbs calculations intact. Data was also missing at the CMU link, so I recreated both data files based on Andrew Gelman's original presidential.asc file. Still, the R chol() call (for Cholesky decomposition) gave errors, then I replaced all NA values with 0's. Code finally worked with this recent fix, and its results seem correct -- a Democrat win is predicted for most states at year 1992 which actually was the case. The code and data files can be found below. Let me know of your questions and comments.


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