After finding out how far off the Colorado state polls were in 2008 I thought it might be interesting to take a look at all of the battleground state polling from '08 to see how the state polling compared to the final results.
I'm using the RCP polling averages from '08 for this. I'm looking at the states included in 538's list of "competitive states."
I'm also including how far off the final Fox News/Rasmussen poll was in parenthesis to shame them.
State | RCP Polling Average | Election Day Result | Difference
Colorado | O +5.5 | O +9 | O +3.5 (Ras O +5)
Florida | O +1.8 | O +2.8 | O +1 (Ras O +3.8)
Iowa | O +15.3 | O +9.5 | M +5.8 (Ras O +1.5)
North Carolina | M +0.4 | O +0.3 | O +0.7 (Ras O +1.3)
New Hampshire | O +10.6 | O +9.6 | M +1 (Ras O +2.6)
Nevada | O +6.5 | O +12.5 | O +6 (Ras O +8.5)
Ohio | O +2.5 | O +4.6 | O +2.1 (Ras O +4.6)
Virginia | O +4.4 | O +6.3 | O +1.9 (Ras: O +2.3)
Wisconsin | O +11 | O +13.9 | O +2.9 (Ras O +6.9)
7 out of 9 states the RCP underestimated Obama with Colorado (3.5) & Nevada (6) being the ones that were most off. Iowa was the only state significantly off in the other direction. McCain overperformed by nearly 6 points. If Romney does the same this time around then Iowa would possibly slip away from Obama. Although that would be OK if he won Ohio, Florida, Virginia, and Colorado.
All 9 Rasmussen polls underestimated Obama and in several cases by a large amount. And this was the final poll. Usually people say "Rasmussen narrative sets until the end when they actually try to nail it..." hmm... they were off by an average of 4.1 points in the GOP's favor.
Something to consider when looking at Rasmussen's polls this time around.
I realized that RCP also has 2004 #s available... I'm just going to include who outperformed the final RCP avg and by how much:
Colorado: Kerry +0.5
Florida: Bush +4.4
Iowa: Bush +0.4
New Hampshire: Kerry +0.3
Nevada: Kerry +3.7
Ohio: Nailed it. (Bush by 2.1%)
Wisconsin: Kerry +1.3
NC & VA aren't on the list as they weren't considered "battlegrounds" at the time (that by itself shows how much better a position Obama is in than Kerry was in '04 ... and remember Kerry was Ohio away from winning the White House.)
Overall the state polling was closer in '04 than in '08 and didn't seem to show a particular bias one way or the other. Although I think it's clear there's something to the Nevada thing; it seems quite likely Obama will out perform the Nevada polls, especially considering what Harry Reid did in 2010.