On "Bradley Effects" and Reverse "Bradley Effects"

There appears considerable debate over whether people are falsely saying that they will vote for or against Obama because of social pressures to tell pollsters certain answers. The "Bradley Effect" was named after LA Mayor Tom Bradley's race for governor in California where apparently many people told pollsters that they would vote for him even though they didn't actually plan on doing so. I am sure that we will be hearing a lot of this discussion this year, but so far the evidence isn't clear. The mistakes seem to be going both ways and it could simply be random errors in the polling. Politico has the story here:

Some observers saw evidence of the Bradley effect right out of the gate this year in New Hampshire. While surveys were close to the mark on the Republican side, polls for the Democratic primary showed Obama with a steady lead over Hillary Rodham Clinton in a contest he eventually lost 39 percent to 36 percent. The average margin of polls taken up until a day before the election projected an 8-point Obama lead.

Exit polls showed that Clinton narrowly edged Obama among voters who made up their decision on Election Day, suggesting that the discrepancies between pre-election polls and the actual vote couldn’t be explained away by a last-minute flood of Clinton support.

Others saw the Bradley effect at work in the Rhode Island primary in early March, where Clinton’s 58 percent to 40 percent victory was also notably wider than expected — the RealClearPolitics polling average showed a margin of 9.7 percent.

In states with larger black populations, such as North Carolina and South Carolina — where polls had Obama leading by 9 points, when he actually won by 28 — there’s even been talk of a reverse-Bradley effect, whereby Obama’s support was underreported in pre-election polls.

Yet for all the worry surrounding the Bradley effect, there is still considerable debate over whether it is a significant cause of polling error — or even a real one at that.

Skeptics point to a number of other elections featuring black candidates where the phenomenon hasn’t surfaced, the most recent of which is the 2006 Tennessee Senate race between Democrat Harold Ford and Republican Bob Corker. In that election, polls showed Corker with a 12-point lead over the African-American Ford just three days out. Ultimately, though, the election margin proved razor thin. . . . .

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