Re: Brad DeLong: Is Mike Allen Really This Ignorant? Assessing Polls Weblogging. Schtevie said:
Brad, are you implicitly saying that you prefer Nate Silver's approach to that of Sam Wang? There is a pronounced difference in suggested certainty between the two and both cannot be correct.
These electoral-vote now-cast point estimates are very similar: they are both aggregating the state-level polls and the national polls, and they are both reaching almost exactly the same conclusions.
The difference in the now-casts is that Wong gives Obama a 95% chance while Silver gives Obama only a 76% chance. The difference in the forecasts is that Wong gives Obama a 90% chance while Silver gives Obama only a 73% chance.
Silver's individual state-level effects appear to be much more correlated than Wong's--Silver believes that if something is leading pollsters to overstate Obama's true strength in Florida his true strength in Ohio is probably overstated as well, while Wong appears to believe that state-level variation is much closer to being independent.
Why this is the case I do not know...