Wednesday, October 22, 2008

MORE ON THE BRADLEY EFFECT

Nate Silver, Newsweek - The Bradley effect is named after Tom Bradley, the former Los Angeles mayor who, in 1982, narrowly lost a bid to become California's governor after having led substantially in the polls. The same pattern reflected itself in other instances involving African-American candidates: Douglas Wilder underperformed his polling in 1989 (but still narrowly won the Virginia governor's race), as did David Dinkins in the New York mayoral race that same year. The theory goes that, in these races, white voters wanted to appear politically correct by telling pollsters they were going to vote for a black candidate when, in fact, they were not prepared to do so. . .

Examples like Bradley and Wilder are nearly a quarter of a century old, and there's no proof that the Bradley effect still exists.

Take the recent study by Harvard fellow Daniel Hopkins, who examined the performances of African-American candidates in major electoral races from the 1980s through the present day. Hopkins found that the Bradley effect did exist during the '80s and early '90s. But it dissipated sometime thereafter; recent black candidates like Deval Patrick and Harold Ford Jr. have performed almost exactly as their polls predicted ahead of time. . .

Then there are this year's primaries. Everyone remembers New Hampshire, when nearly all polls predicted a big win for Obama, but Hillary Clinton emerged victorious. That was a bad day for the pollsters-and for Obama, who underperformed the Pollster.com composite average by 9 points. . . What fewer remember is what happened two weeks later in South Carolina. In that case, the Pollster projection had Obama winning by 15 points-but he won by 29. That 14-point error was actually of greater magnitude than the mistake in New Hampshire, if less noticeable because the polls hadn't picked the wrong horse.

South Carolina was not the only state in which Obama overperformed his polls. They significantly underestimated Obama's margin in essentially every Southern state, including Virginia, Georgia and North Carolina, as well as a couple of states outside the South, like Wisconsin, Indiana and Oregon. On balance, the polling during the primaries underestimated Obama's support by 3.3 points when compared to the Pollster averages in those states. . .

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