If the Dems are polling in a city such as Philadelphia, wouldn't they have to have a sampling skewed towards Dems because there ARE more of them in Philly.
I guess my question is: does oversampling mean above an equal average? or does it mean above the known sampling ratios?
I’ve wondered the same thing: if you call up 1,000 voters on a supposedly random basis, and you get 70 percent Dems and 30 percent Republicans, and they all tell you they are going to vote straight party line, does that mean you have established accurately that the Democrat is going to receive something close to 70 percent of the vote?
But I know that pundits are always talking about “sampling” and “weighting” the polls. So I assume the “weighting” comes in when they get the rough numbers, and then apply turnout ratios (and probably other factors) to the 70-30 split and come up with something a bit different.
What I see conservatives hanging their hats on this time is that many pollsters are using 2008 turnout numbers to weight the results; and in 2008 the proportion of Republicans voting was far less than in, for instance, 2010.
Then again I could be completely wrong.