For a good portion of October, Gallup found Republican Mitt Romney with abnormally large leads on President Barack Obama in the aftermath of Romney’s tremendous first debate performance. It came right as Gallup switched to a likely voter model, and it earned Gallup a significant amount of criticism from the left. Today, Gallup was rated 24th of 27 national pollsters this election season. Gallup’s final projection put Romney up by a point, but it still different from the reality of Obama winning the popular vote by more than 2 points.
The reason Gallup got it wrong is simple: Its likely voter model found a drastically different electorate than the one that actually showed up.
Here’s a look at the Gallup-projected electorate:
Compare that with the actual results from the exit polls. Most significantly, Gallup found wildly different party and racial makeups than the ones that voted on Tuesday.
Gallup underestimated the Democratic percentage by 3 points and overestimated the Republican percentage by 4 points. It overestimated the white vote by an astounding 6%, underestimated the black vote by 2%, and underestimated the Latino vote by 3%.
Finally, Gallup also clipped the age 18-to-29 vote by a similarly astonishing 6%.