Are the presidential polls skewed?

[nomoon]

I just uploaded an updated graph for the national polls. I only included polls that extended into November. This excluded the Gallup poll.

The CNN poll, which showed a tied race, is quite an outlier, with a Democratic advantage of 12 points. Drudge still list this as a "D+11" poll, though, I looked at the actual polling data, which shows that it is really a D+12 poll. Page 29 of the CNN report states:

Quote:Among those likely voters, 41% described themselves as Democrats, 29% described themselves as Independents, and 30% described themselves as Republicans.

A recent Gallup report states that there was actually a R+1 advantage for likely voters (sorry, I don't have a link). If I've interpreted that correctly, then one might extrapolate a Romney lead of +4 based on the recent polling results. Then, again, this whole hypothesis could be completely wrong.