Photo: The Guardian
Eight organizations receive an “A” rating:
538 pollster ratings. 538 gives every pollster an A-F grade. Gallup got a C+. Pew Research got a B. Rasmussen Reports got a C. Who got As? Selzer & Company, Field Research Corporation, Ciruli Associates, SurveyUSA, Grove Insight, Blum & Weprin Associates, Elway Research, and National Journal.
The scores were determined by comparing the poll results with the final election results. The average poll was off by 5.3 percentage points from the final election outcome.
The very best pollsters are about 1 percentage point more accurate than the average pollster over the long run. The very worst pollsters are off by 2 to 3 points of error compared to the average. The worst polls are more worse (further below average) than the best polls are good (above average). That's because, while there are intrinsic limits to how accurate any poll can be (because of sampling error and other factors), there are no shortage of ways to screw up.
See 538 full list of ratings here