The Pew Research Center and Rasmussen Reports were the most accurate in predicting the results of the 2008 election, according to a new analysis by Fordham University political scientist Costas Panagopoulos. The Fordham analysis ranks 23 survey research organizations on their final, national pre-election polls, as reported on pollster.com.It's not an accident that 17 of the 23 polls overstated Obama's vote margin. And keep in mind that this is a comparison of their final polls, which is when the more egregiously pro-Democratic organizations suddenly start cleaning up their act a little so they don't get it too noticeably wrong. And where are the Pew and Rasmussen polls today?
On average, the polls slightly overestimated Obama’s strength. The final polls showed the Democratic ahead by an average of 7.52 percentage points — 1.37 percentage points above his current 6.15-point popular vote lead. Seventeen of the 23 surveys overstated Obama’s final victory level, while four underestimated it. Only two — Rasmussen and Pew — were spot on.
Rasmussen has Obama 50, Romney 45. Pew has Clinton 29, Obama 16, and Michelle Obama 15, but their poll concerns who gave the best speech at the DNC so I don't think there is much to be learned from that. What might be informative would be to look at where the 23 polls were in the middle of September 2008 and compare them with the current polls. I may do that at some point, but not today.