Lies, Damned Lies, Statistics, and CBS Polls
How does McCain trail Obama in a recent poll by 6 percentage points among overall voters, yet hold a lead over Obama among independent voters by 8 percentage points, with 12% of Democrats saying they will vote for him (up from the 8% who voted for Bush in 2004)?
That's easy. All it takes is CBS's "creative" polling techniques. Ed Morrisey reports:
... That last number should have tipped CBS that their sampling was off … again. If McCain leads among independent voters by eight points, it makes little sense that he would trail overall by six. When adding in the 12% of Democrats who plan to defect to McCain, the overall number appears impossible.
Of course, with the CBS poll, nothing is ever impossible; it’s just a matter of juggling the numbers. In their original sample, they surveyed 930 registered voters. The registration comprised 27% Republicans, 40.5% Democrats, and 32.5% independents. CBS thought those numbers looked incorrect, and so “weighted” the numbers to get a better representation of how CBS sees the electorate. The final breakdowns?
Republicans - 25.5% Democrats - 41.5% Independents - 33%
CBS expanded the gap between Democrats and Republicans from 13.5% to 16%, while edging up independents slightly. Small wonder, then, that the Democrat leads in this poll. And that is among registered voters, not the far-more-predictive likely-voter samples, which tend to disfavor Democrats...