This latest dispatch from WTTG in DC ("McDonnell Making Comeback in Polls") is a shining example of the problems with averaging polls from different pollsters, using different samples, and hyperventilating whenever that average moves.
To wit:
McDonnell may have weathered the storm. The website RealClearPolitics.com, which had his lead at 12 points when the college paper controversy began and then sunk to a dead heat, now has him up seven points over Deeds. The site now has McDonnell leading the race 50 percent to Deeds' 43 percent.
They are referencing this chart:
...and reaching for the most convenient explanation possible that was fed to them by McDonnell's crack team of press staffers--that is, the furor over McDonnell's thesis has died down.
Unlike approval polls, which are posted from multiple pollsters on a near-daily basis, averaging election polls is easily affected by which pollster releases when. Creigh's sudden surge in the RCP average is the direct result of the latest SurveyUSA poll which showed Deeds down 11. The race appeared to tighten because the last SurveyUSA poll conducted in September (showing Deeds down 12) was pushed out of the average by pollsters showing an average margin of 4-6.
In short, the fluctuation in polling averages can be entirely explained by the addition and dropping of SurveyUSA polls, which have consistently shown Deeds with a double-digit deficit even as other pollsters show a narrower lead. Now, if we go to Pollster and turn on the more sensitive option, we also see this trend (see that widening on the far right? That's what Fox5 is talking about):
Now we take out SurveyUSA:
Wow! Notice how all the points where it seemed McDonnell had a huge double-digit lead (points that corresponded to when SurveyUSA posted a poll) have vanished!
This election is not about persuasion, it is about turnout. This doesn't mean that SurveyUSA is wrong about how the electorate is feeling, it means that they have a different idea of who will show up to vote. The chief difficulty in polling post-Obama Virginia is the turnout question.
Bonus: The article also said "Deeds is from Bath County in southwestern Virginia". Of course, if one was to start driving from Bath County in a southwesterly direction, he would still have over five hours of Virginia to go.
