Well, since I noticed there are two families of polls out there, and only one family will be proven right next Wednesday, I have decided to take the RCP average for the national polls and split it into the “traditional” poll of polls and the “extended” poll of polls. My original posts on what the difference is between the two families of polls are here and here.

But basically those daily tracking polls in the ‘traditional’ family use historic voting trends to weight things like party ID affiliation in their turnout models.  The ‘extended’ family of polls are based on the unproven assumption this year’s turnout will favor the Dems by 2-3 times the highest historic advantage ever seen in memory. Over the years there have been times when the Democrats have seen up to a 4% edge in voter turnout. The polls in the ‘extended’ family assume a Democrat edge of 8-12% in their turnout models – crazy, eh?

Well, we will see which polling approach pans out. But the RCP approach of averaging all these polls is mathematically wrong. The results will track to one family or the other. So I give our readers the Bi-Poller report on the two family of polls.

Strata-Sphere Extended: 7.3%

First, for the Obama supporters we provide the ‘extended’ poll of polls. This group includes the following daily tracking polls (with today’s horse race numbers in parentheses): Rasmussen Reports (Ob +5), Gallup (Expanded) (Ob +10) and ABC News/Wash Post (Ob +7). Therefore the Extended Poll average for today is Obama +7.3% (identical to the RCP average).

Strata-Sphere Traditional: 4.8%

Now, for the McCain supporters we have the historically proven polling method. This group includes the following daily tracking polls (with today’s horse race numbers in parentheses): Gallup (Traditional) (Ob +5), Reuters/C-SPAN/Zogby (Ob +5), Diageo/Hotline (Ob +8), IBD/TIPP (Ob +3) and GWU/Battleground (Ob +3). Therefore the Traditional Poll average for today is Obama +4.8% (not very close to the RCP average).

RCP National Average: 7.3%

RCP has other, non-daily tracking polls, in their average. I have decided to just go with the daily polls for this analysis.

As can be seen the RCP average, by mixing polls of different families, could be off by quite a bit. And as this race tightens in this final week, even a few percentage points could mean a big difference in accurately predicting the outcome next Tuesday. I will update this each night once all the daily tracking polls are posted at RCP.

Tags: 2008 Election, Nightly Bi-Poller, Polls