Are the presidential polls skewed?

[nomoon]

Here is a plot of Saturday's (11/3/12) data for Ohio. There's not much of a trend to plot, but almost all of them are assuming a Democratic turnout advantage of six to nine points. That seems rather big. I really wanted to include Rasmussen, but I couldn't find the party turnouts for their Ohio poll. As given, the polls state that Obama has a slight, but definite lead in Ohio. However, if the assumed turnouts are unrealistic for Democrats, then Romney could very well win this state.



Does anyone know what the party turnouts were in Ohio for 2004, 2008, and 2010? I'd love to know those numbers as boundary conditions. I thought that I heard a TV news speaker this morning mention that Ohio has more registered Democrats than Republicans, so maybe we can assume that Ohio should legitimately have Democratic weighting advantage that is higher than the national average, but that isn't telling me much.


I've also wondered about the pollster's explanations if the turn out models turn out to have be unrealistically favorable towards the Democrats. The Bradley Effect (Forbes, "Does the Bradley Effect Overrate Obama in the Polls?," 9/19/12) might be one explanation given. Here is a summary from Wikipedia

Quote:The Bradley effect, less commonly called the Wilder effect,[1][2] is a theory proposed to explain observed discrepancies between voter opinion polls and election outcomes in some United States government elections where a white candidate and a non-white candidate run against each other.[3][4][5] The theory proposes that some voters will tell pollsters they are undecided or likely to vote for a black candidate, while on election day they vote for the white candidate. It was named after Los Angeles Mayor Tom Bradley, an African-American who lost the 1982 California governor's race despite being ahead in voter polls going into the elections.

The Bradley effect might explain overall vote percentages, but I'm not sure if it would affect Democratic voters disproportionally, which would seem to be needed to explain the difference in party turnout.