The CNN Poll of Polls

Did you know there's one poll that claims to have no margin of error? Yes! It's the CNN National Poll of Polls.

chart by Jim Whiteside

How is that possible? By combining up to eleven different polls, it increases the sample size. That reduces the margin of error. Once the margin drops below half a point, you can say with a high degree of confidence that the results are accurate...but not perfect! There's still a margin of error. It's just very small.

Adding to its significance are the polls included in the CNN poll:

1. American Research Group
2. Franklin & Marshall
3. IPSOS-McClatchy
4. Fox/Opinion Dynamics
5. AP/GfK
6. Pew
7. CNN/ORC
8. ABC/Washington Post
9. Reuters/C-SPAN/Zogby
10. Gallup
11. Diageo/Hotline

There are several new factors, however, that may reduce its accuracy in this unusual election:

1. The Bradley effect
2. The inability of pollers to accurately sample cell phone users
3. Unknown turnout percentages for enthusiast new voters
4. Unknown turnout percentages for enthusiast young voters
5. Unknown turnout percentages for enthusiast Black voters

The Bradley effect suggests that nearly all of the undecided voters will break for the white candidate. Since the latest poll of polls has Obama at 51%, that shouldn't be problem unless the race tightens. The cell phone problem, however, will take several election cycles to clarify.

The effects of enthusiasm, however, have always been overestimated. Young, new, and even Blacks have always disappointed their believers in the past. Since Obama is Black, there's good reason to think this time might be different, but even that's not a sure thing.

Since it's not clear how the pollsters are weighting all of these factors in their sampling techniques, CNN's claim of a zero margin of error can only be taken with a grain of salt. Even if the election were held tomorrow, it's still possible that McCain would win.