Nate Silver’s FiveThirtyEight Blog
One of the most interesting things in elections is seeing how well the polls and predictions match up with actual results. It’s an interesting application of statistics and probability, and one man in particular, Nate Silver from the FiveThirtyEight blog, nailed every single state (except Florida, which still hasn’t been called as of this posting). The precise methodology in which Silver aggregates and analyzes poll data to make his predictions are complex, but his blog is well known for very clearly explaining their probabilities in very clear and concise terms. And he makes it explicitly clear that conditional and marginal probabilities definitely play a huge role in his models.
Much of Silver’s methodology apparently comes from his time working on baseball stats, but Silver claims that he “assign[s] each poll a weighting based on that pollster’s historical track record, the poll’s sample size, and the recentness of the poll” [From the old FiveThirtyEight website]. Naturally, many factors come into play when calculating probabilities, and it relies on a whole myriad of conditions, such as economic factors and demographic data. Although calculating this probability is more complicated than just using Bayes’ Rule, the concept is similar, just that there are many variables to consider. Almost all his blog posts have very detailed stats, yet they are explained in terms that is easy to understand, and so it’s better to see Silver’s explanations for his results than to have another layer of explanation. It is clear, however, that he uses carefully uses the basic rules in statistics and painstakingly ensures that the data he uses is accurate (while making it clear if he believes there to be some source of error).
The FiveThirtyEight blog is all about probabilities that a candidate will win based off poll data and many other factors, and when the blog first launched in 2008, many statisticians believed this methodology to be flawed in many ways. But after highly accurate results in two elections, it’s clear it can be done correctly, and more and more pundits and politicians are closely following FiveThirtyEight.
https://docs.google.com/a/cornell.edu/document/pub?id=1Czyh9Y5pxeANjPsxuBIRrnK-hjdFPO5e6DcxzlufPaU
http://www.huffingtonpost.com/tarun-wadhwa/nate-silver-election-predictions_b_2090909.html
http://fivethirtyeight.blogs.nytimes.com