I don't mean to argue that Nate Silver had a "big Bayesian model behind all that." But if sample size and recency increase the reliability of polls, you can objectively measure how much they do and it seems that using Bayesian methods you could create an objectively best prior weighting system, which seems like the point that Vaniver was making.

I'm not immediately familiar with the math but it seems odd to me that it would be much more work to do a regression for a "best prior" than to come up with an ad hoc method, especially considering that "expert judgment" tends to be really bad (at least according to Bishop and Trout ).

Of course, I should probably wait to disagree until he [Nate Silver] gets something wrong.