The commentariat's topic du jour is this AP story which cites a study conducted in conjunction with Yahoo!, Knowledge Networks and Stanford University and which reports that "Statistical models derived from the poll suggest that Obama's support would be as much as 6 percentage points higher if there were no white racial prejudice." Here are some thoughts I have on the matter:
1. It is irresponsible to cite this study without fully disclosing its methods or making it subject to peer review, particularly as it appears to use a rather convoluted soup of statistical and inferential techniques.
2. The study appears to be one of all adults, rather than registered or likely voters. Expressions of racial prejudice have a strong inverse correlation with education levels, and so do turnout rates. Therefore, even if it is true that Barack Obama's race puts him at something like a 6-point disadvantage with the population as a whole, the margin is probably more like 4-5 points among likely voters.
3. A related and unresolved question is how many persons will vote for Barack Obama because he is black. Such behavior would probably be more implicit and harder to ascertain than voting against a candidate because of racial prejudice. For instance, Obama's biography is significantly more compelling because he is black (actually, bi-racial), and his change message is probably somewhat easier to sell because he looks different than other (e.g. white) politicians. If he were white, in other words, Barack Obama would not be Barack Obama. Moreover, there may be some people who explicitly vote for Obama because they think it will advance a goal of racial equality, present a different face to the world, and so forth. In the absence of sufficient detail on the study's methodology, it is impossible to know whether these things have been accounted for.
4. One should be very careful not to confuse a study like this with the Bradley Effect. Of course some people are racist, and will vote against Obama because he is black -- I have met some of them. But the Bradley Effect concerns something different -- whether such people are likely to lie about their behavior to pollsters. There is simply no empirical evidence that the Bradley Effect exists any longer. It did not exist in the primaries, and it did not exist in the 2006 Senate race in Tennessee, which was perhaps the most racially-tinged contest of the past decade (in fact, Harold Ford slightly outperformed the late polls).