Which Polls Fared Best (and Worst) in the 2012 Presidential Race
fivethirtyeight.blogs.nytimes.com
fivethirtyeight.blogs.nytimes.com
Whether or not Gallup are delusional (or not) is up for debate.
Step 2: Add results.
Other than simple math, I'm not seeing what there is to mess up.
The math is the easy part here. All the rest is hard.
How can you reach as many people as possible? How can you make sure that you reach a random sample of people? If you give up on that because it’s pretty hopeless, how can you make sure that the characteristics you pick to build your sample (for example age, gender, race, etc.) actually matter, are correctly chosen and that you have the right information about how your sample should look when it comes to those characteristics? (This problem can be rephrased as: How do you make sure your sample is representative? It is, however, important to unpack the complexity involved in that.) How do you know that those who tell you they will go vote will actually vote?
That’s not a complete list of problems. As you can see there are more than enough opportunities for error here.
Now, given Gallup’s poor performance compared to other polls I do not want to excuse them. They screwed up, there is not question about that. I do not think, however, that there is any need to make up conspiracy theories.
Ouch. So their "transition to likely voters" estimation is just completely off.
That's the same problem we're dealing with here. Presidential votes only happen once every four years, so it can be difficult to validate any sort of model. A hundred pundits make a hundred different predictions. And dozens of polls make different predictions as well. Does that mean that the pundits and the polls which ended up being closer to the truth are more accurate or does it just mean that they were lucky?