KATE ZERNIKE ESSAY

ELECTION DAY IS approaching and polls project a victory, possibly a big one, for Barack Obama.
Yet Democrats everywhere remain anxious. They’ve seen this before. Remember how the exit polls in 2004 predicted President John Kerry?
The anxiety is more acute this year because Senator Obama is the first African- American major-party presidential nominee. And even pollsters say they can’t be sure how accurately polls capture people’s feelings about race, or how forthcoming Americans are in talking about a black candidate.
In recent days, nervous Obama supporters have been worried over a survey - widely disputed by pollsters - that concluded racial bias would cost Mr. Obama six percentage points in the final outcome. Current polls give him a lead averaging around eight points.
If he loses, it wouldn’t be the first time polls overstated support for an African-American candidate. Since 1982, people have talked about the Bradley effect, where even lastminute polls predict a wide margin of victory, yet the black candidate goes on to lose, or win by a very small margin. In the case that lent the phenomenon its name, Tom Bradley, the mayor of Los Angeles, lost his race for governor of California, the assumption being that voters lied to pollsters about their support for an African-American.
But pollsters and political scientists say concern about a Bradley effect is misplaced. It obscures what they argue is the more important point: there are plenty of ways that race complicates polling. Considered alone or in combination, these factors could produce an unforeseen Obama landslide with surprise victories in the South, a stunningly large Obama loss or a recount-thin margin.
Among the factors is something called the reverse Bradley, in which polls understate support for a black candidate, particularly in regions where it is socially acceptable to express distrust of blacks. Then there are the voters not captured by polls. Research shows that those who refuse to participate in surveys tend to be less likely to vote for a black candidate. The race of the questioner, too, affects a poll.
In 1982, exit polls had Mayor Bradley so likely to win that newspaper headlines called him the victor. Yet he lost, narrowly. There emerged what seemed like a pattern: a number of polls found more support than there actually was for Harold Washington in the 1983 Chicago mayoral race; for David N. Dinkins in the 1989 New York mayoral race; and for L. Douglas Wilder in the 1989 Virginia governor’s race.
Were people so afraid to appear bigoted that they lied to pollsters, thinking it more socially acceptable to support a black candidate- Pollsters and political scientists have long questioned that assumption.
“We have no evidence that people lie to us,” said Joe Lenski, executive vice president of Edison Media Research, which conducts the exit polls the television networks use. He and others say that discrepancy in the polls has more to do with which people decline to participate, or say they are undecided.
Andrew Kohut, the president of Pew Research Center, conducted a study in 1997 looking at differences between people who readily agreed to be polled and those who agreed only after one or more callbacks. Reluctant participants were significantly more likely to have negative attitudes toward blacks - 15 percent said they had a “very favorable” attitude toward them, as opposed to 24 percent of the ready respondents. “The kinds of people suspicious of surveys are also more intolerant,” Mr. Kohut said.
Whatever its causes, the Bradley gap seems to be disappearing.
In a new study, Daniel J. Hopkins, a postdoctoral fellow at Harvard University, considered 133 elections between 1989 and 2006, and found that blacks seeking office before 1996 suffered a median Bradley effect of 3 percentage points. Blacks running after 1996, however, performed about 3 percentage points better than their polls predicted. Mr. Hopkins argues that the changes in the welfare laws in 1996 and the decline of violent crime reduced two sources of racial animosity among whites.
In this year’s Democratic primaries, University of Washington researchers found a Bradley effect in three states, but a reverse Bradley effect in 12 .
The results tended to correlate with the black population in a state: blacks made up 15 percent or more of the population in almost all the states where the polls showed less support for Mr. Obama than there actually was; in the three states where polls showed more support than there was, less than 10 percent of the population is black.
Anthony Greenwald, one of the researchers , sees a cultural dynamic at work: the states where polls under-predicted support for Mr. Obama were generally in the Southeast, where the culture has more stubbornly favored whites, so the “right” answer there was to choose the white candidate. In the three states where polls in the study over-predicted support for Mr. Obama - Rhode Island, California and New Hampshire - “the desirable thing is to appear unbiased and unprejudiced,” Mr. Greenwald said.
The Bradley effect “has conceptually mutated,” he said. “It’s not something that’s an absolute that we should generally expect, but something that will vary with the cultural context and the desirability of expressing pro-black attitudes.”
Many experts argue that race does not play a huge role in polling or voting this year, because the economy has emerged as such a dominant issue, and Mr. Obama is not primarily identified by his race.
But most of what the experts know, they know from polls. And even in the least complicated years, polling is a recipe with a good dash of “Who knows?”