I know Nate Silver had something similar to this, but I wanted to do my own pollster analysis. Each poll here is taken October 15 or later, because the state of the race stabilized around then after the first debate fallout. I also only used each pollster's last poll of the cycle. With that to be said, here are my rankings. All numbers are by margin, not Democratic vote total. All numbers are too Republican unless noted.
Quit Polling Immediately!
These firms released one poll in the last two weeks, and it was very far off.
Baydoun Foster: 10 points off in Michigan
Roanoake: 8 points off in Virginia, 10 points off in Virginia Senate
University of Iowa: 7 points off in (where else?) Iowa
Sunshine State News: 6 points off in Florida, 8 points in Florida Senate
Omaha World Herald: 13 points off in Nebraska
Boston Globe: 7 points off in Massachusetts
UMass: 8 points off in Massachusetts
New England College: 10 points off in New Hampshire Gov. Although they were within 2 in the Presidential. I think there was lots of late movement to Hassan so maybe I'll give them a pass.
Detroit News: 6 point miss.
Category 2: Small Pollsters Who Did OK
St Norbert: A stinker, 9 points off in Wisconsin Senate, but 2 points too favorable to Obama in the Presidential.
Susquehanna: Being generous here with my definition of OK. 8 points off in Pennsylvania Senate, but at least they were within 5 in the Presidential.
Howey Poll: One of Indiana's few pollsters, they were 4 points too Republican in the Governor's race but 5 points too Democratic in the Senate race.
Elway: 4 points off in Washington's Gubernatorial election despite their great reputation.
Mitchell: 4 points off in Michigan.
Category 3: Small Pollsters You Can Trust
Columbus Dispatch: 1 point off in the Presidential, nailed it in the Senate.
Ohio University: Also 1 point off in the Presidential.
Des Moines Register: Another 1-point miss.
Ohio Poll: 2 points off in Presidential and Senate.
Ohio News: 2 points off in Senate. Lots of strong Ohio pollsters.
Morning Call: 2 point miss in Presidential, 3 in Senate.
Franklin and Marshall: 2 point miss for President, nailed the Senate contest.
EPIC-MRA: 3 points off in Michigan.
UNH: 3 points in Presidential, only 1 for Governor.
Elon: 2 points too blue for Obama, 2 points too red for McCrory.
Marquette: 1 point miss in the Presidential (too favorable to Dems), 2 in the Senate (too favorable to Thompson).
Philly Inquirer: a point too blue for Obama, two points too red for Tom Smith.
Civitas: Despite being a Republican pollster, they were one point too favorable to us in North Carolina.
Western New England University: 3 points too favorable to Scott Brown.
Strategies 360: Dem internal pollster but two points too red.
MassINC: 1 point too red.
The Washington Poll: 1 point too favorable for Governor.
Washington Post: 2 points blue for Senate, 1 for President.
The Crappy Major Pollsters:
First, an award to every poll by a major pollster that was eight or more points off. In this category we have:
8 points: Rasmussen Colorado (the only Presidential one), Connecticut SurveyUSA (SUSA), Florida PPP, PA Rasmussen,and PPP New Hampshire Governor.
10 points: Florida Rasmussen and Gravis
11 points: Missouri PPP and We Ask America (WAA)
12 points: Connecticut Mason-Dixon
13 points: Missouri Mason-Dixon
Now for the actual pollsters.
14th place: Mason-Dixon: Consistently Republican-leaning (all 12 of their polls were 3 points or more too favorable to Team Red, with 9 of the 12 five points off or more), Mason-Dixon is just an awful pollster. They missed by an average of 5 points in their Presidential polls and 7.1 in their downballot polls. Just all-around abysmal. Ignore them.
13th place: ARG!!!: Our favorite pirates only polled the Presidential election, and if you only count Presidential polls they were even worse than Mason-Dixon. They missed by an average of six points, with their best (if you can call it that) poll a five point miss in Nevada.
12th place: Gravis: They came out of nowhere to skew the polling averages toward Republicans. A respectable 3 point miss average in Presidential polls, including nearly correct polls in Florida, Pennsylvania, North Carolina, Iowa, and New Hampshire, but a 7.3 point miss in three statewide contests.
11th place: FOX: They only did two polls, so the sample size is small, but they missed by an average of 4.5 points. Not so good.
10th place: Rasmussen: It speaks volumes about this year's cycle that Rasmussen is only the fifth worst. A 4.2 average miss in Presidential polling and a 5.2 average miss in statewide contests. Despite 28 polls, only one was spot-on and none were Democratic-leaning.
------------------This is the cutoff line; I'd ignore all pollsters above the line and at least take note of those below.
9th place: Purple Strategies: Another new pollster this cycle, they also only polled twice, and missed by 3 and 4 points in their two polls.
8th place: We Ask America: Their 1.5 point average miss in Presidential polling was impressive. Every state was within two points of their final poll. So I'd count them as one of the best, except for their other polls. While Missouri was a tough contest to poll, missing by 11 is inexcusable. Their average miss was 5.5, nothing to brag about. But they are better pollsters than many give them credit for nonetheless.
7th place: THE POLLING AVERAGES: Average misses of 2.4 for President and 4.3 for Senate/Governor are pretty weak for polling. Only one race was spot on (Ohio President), while five were within one point. I'll show the polling averages for every race at the end of this diary.
6th place: SurveyUSA: SUSA also gets a bad rap, but they're a decent pollster. They were consistently off by three points. But sometimes too red and sometimes too blue, which can make it difficult. 2.57 Presidential miss (but no partisan lean) and 3.9 statewide races miss.
5th place: Marist: It depends how you calcuate the pollster score for Marist. If one adds up the total miss including partisan lean, their Presidential polling missed by only 1 point. However, calculating based on absolute value gives a miss of 2.5, because they were 3 points too Democratic in Ohio. Either way, 2.5 for President and 3.5 for statewide races is decently impressive.
4th place: CNN: They don't get to be any higher than this because they only did Presidential polling, and only in three states. However, an average miss of 1.67 is very impressive.
Bronze Medal: Suffolk?!: Because of their small sample size (two polls), they won't go higher than third place, but they were actually the best pollster of all, despite claiming Virginia/Florida/North Carolina were Safely Republican. Nailed it in Massachusetts Senate and were a point blue in Ohio Senate.
Silver Medal: PPP: 1.56 points off in Presidential polling and 3.33 in statewide contests. A few bad outliers in Florida/Missouri Senate and New Hampshire Governor, but every other poll was within four points (and they did 24 polls!) and 19 of the 24 were within three. They are the most pro-Democratic of any polling firm in terms of bias, but they still had 13 polls too Republican and 8 too Democratic.
Gold Medal: Quinnipiac: They don't poll every state, but the ones they do poll they are excellent at. 1 point miss in their three Presidential polls, 2.5 points in their four Senate polls.
Now, for fun, the error in polling averages for various contests. All averages were too Republican.
9 points: Missouri Senate (admittedly a tough race to poll due to Todd Akin)
7 points: New Hampshire Governor (late movement to Hassan)
7 points: Connecticut Senate (I do think Sandy helped in the NYC area, but it also may have been some bad polling. But when Quinnipiac and SUSA both miss by six points or more, there's an issue somewhere).
7 points: North Dakota Senate (very few polls here)
7 points: Florida Senate (not sure why this was)
5 point: Michigan President
4 points: Montana Senate, Massachusetts Senate, Missouri Governor, Nevada President, New Hampshire President
3 points: Pennsylvania Senate, Nevada Senate, Virginia Senate, Wisconsin Senate, Montana Governor, North Carolina Governor, Virginia President, Iowa President, Colorado President
2 points: Florida President, Wisconsin President, Minnesota President
1 point: Ohio Senate, Washington Governor (other than these two, Democrats outdid the polls by 3 points or more in every Senate/Governor contest which is pretty amazing), Missouri President, Pennsylvania President, North Carolina President
Perfection: Ohio President
Ohio must be the easiest state to poll or something. Anyway, there you have it.