How will undecided voters break, and will racial attitudes color their votes?
We've seen an enormous amount of speculation but little evidence based on data, so let's try to tip the balance back to empirical evidence.
Thanks to the Diageo/Hotline tracking poll data, we can model individual vote choice and see what we would expect of undecided voters.
During October 3-11 our colleagues at the Diageo/Hotline poll included a racial attitude question we had previously used in the Big Ten Battleground survey in September and which NBC/Wall Street Journal used in January. That question was shown in both the earlier polls to have a statistically significant effect on vote choice, even after controlling for other political attitudes and demographics.
The question text is: "I'd like you to tell me whether you strongly agree, somewhat agree, somewhat disagree or strongly disagree with the following statement. ... African Americans often use race as an excuse to justify wrongdoing"
58% of the total sample, and 61% of whites agree either strongly or somewhat. (For comparison, 56% of hispanics and 40% of African Americans agree strongly or somewhat.)
I model the vote choice for those who expressed a preference with a model using a variety of attitudes and demographics, including favorability to Obama and McCain, party id, marital status, kids at home, education, race, age, sex, church attendance, region and urban, suburban or rural residence. Then I added the racial attitude responses from the "black excuse" question. To check against people hiding their feelings by refusing to answer the "black excuse" question I also included a variable to capture the effect of refusal to answer.
This model produces a predicted probability of voting for McCain or Obama, including predicted probabilities for those who had said they were undecided or who refused to respond to the vote question. From this we can estimate the likely vote of undecided, and compare the estimates to the responses of those who gave a vote preference in the survey.
Bottom line: Undecided and refuse to say voters are estimated to break 50% for McCain and 50% for Obama. As even as it gets. There is no evidence here of a large bias towards McCain that is hidden within the undecided respondents.
Nor is there evidence of a pronounced racial bias among these undecided voters as compared to the public at large. Among the undecided 27% strongly agree and 32% somewhat agree on the "black excuse" item. For the public as a whole 26% and 32% give the corresponding responses.
The model does a good job predicting survey response as well. 97% of both Democratic and Republican voters are predicted by the model to vote that way. For those who say they only "lean" towards one party or the other, 77% of Democratic leaners and 80% of Republican leaners are predicted to vote as they lean. The symmetry of results here suggests that there is not a visible bias in the model estimates for either party or for intensity of preference.
Finally, what happens if we ignore racial attitude and predict vote among the undecided without it? The split is 52% Obama to 48% McCain. So at most the impact of incorporating racial attitude in the model is a rise of 2% for McCain among undecided. Given the sample sizes involved, that is well within the margin of error. And if we take out candidate favorability from the model we get estimates of 52-48 without racial attitude and 53-47 with racial attitude.
So what can we conclude? There is no evidence of a hidden support for McCain among undecided voters. They split more evenly than does the "decided" pool of respondents, who split 54-46 in this sample (Oct 3-11) but that's well within normal expectations and is a modest difference in any case.
Second, the role of racial attitude is important at the individual level, but the aggregate consequence is extremely modest. Some are moved away from Obama yet others are moved towards him. And among the undecided, the distribution of opinion on this measure of racial attitude is virtually identical to that in the population.
In a year of endless discussion about racial effects there has been far more speculation and far less data analysis than is good for us. Let's put our data on the table before continuing to opine about this subject.