Articles and Analysis


Bradley-Wilder: New Data on Interviewer Race

Topics: Adam Berinsky , Bradley/Wilder , Gary Langer , Kathy Frankovic

Just yesterday, I expressed a bit of frustration that much of the recent media focus on the "Bradley-Wilder Effect." Much of it, and much of the debate in the blogosphere, inevitably turns on looking backward at what surveys did or did not miss 20 or 30 years ago. Instead, my hope is that pollsters will share with use new measurements based on their current survey data that can help us determine whether any such "effect" is in store for 2008.

Today, the ABC Polling Unit and its director Gary Langer posted data indicating that on at least one measure, the 2008 surveys are not yielding evidence of the "effect."

First, a bit of background for those who are just tuning in: The pattern seen in surveys in the 1980s and early 1990s was that in races pitting black Democrats against white Republicans, the final public opinion polls would accurately forecast the percentage of the vote for the African American candidate but would understate support for the white candidate. One piece of evidence that the effect was real was the apparent presence of "race of interviewer effects." Here is the way I described the issue in a column earlier this year:

Pollsters concluded [20 years ago] that racial attitudes were at work in the Bradley-Wilder effect when they observed that white respondents tended to report different vote preferences depending on whether the interviewer was black or white.

The best known study of this phenomenon -- a 1989 Public Opinion Quarterly article [PDF] based on surveys of the Virginia governor's race -- closed with an "unambiguous recommendation: survey organizations must record the race of interviewers and check for these effects whenever they conduct polls in black-white electoral contests."

That is exactly what Langer and ABC have done with 7,281 white respondents interviewed so far this year, and they see no evidence of race of interviewer effects in their recent surveys:

Among registered voters in a dozen national ABC/Post polls this year, 53 percent of white respondents told white interviewers they supported McCain - as did 52 percent of white respondents speaking with black interviewers. Forty-one percent of whites told white interviewers they supported Obama; an identical 41 percent said the same to black interviewers. And 93 or 94 percent of back respondents backed Obama, regardless of the interviewer's race. (It's unclear, moreover, how well respondents can even tell the interviewer's race in a telephone survey. In one of our recent polls 55 percent identified it correctly, but 23 percent were wrong and 22 percent declined to hazard a guess.)

The pollsters at CBS News did a similar analysis earlier this year and also found some "limited" evidence of race of interviewer effects in surveys conducted in 2007, but not in 2008, and then only on questions asked about the primary election contest between Clinton and Obama. Here is the way CBS polling directory Kathy Frankovic described that evidence recently (emphasis added):

This spring we aggregated several polls and looked at the interaction between the race of the interviewer and the race of the respondent and how that might impact vote choice. We did find some race of interviewer effects among white respondents, but it was relatively small, and appeared limited. White Republicans, the oldest white voters and the youngest white voters, and whites in the South and the West, showed no race of interviewer effect. There was some among white voters who were Democratic identifiers, those who were between the ages of 44 and 64, and those who lived in the Northeast or Midwest. However, more recent polls haven't found a significant race of interviewer effect. But clearly we need to look at this on a regular basis.

Again, pollsters including Langer and Frankovic continue to debate the theories and evidence behind the apparent "effect" seen 20 or so years ago. That is an interesting discussion, but not particularly relevant to the 2008 election. The bottom line: if present day surveys are yielding little or no evidence of race of interviewer effects, that is a big strike against the possibility of a pronounced "Bradley effect" this year.

Bonus: And speaking of looking backward, friend-of-Pollster Adam Berinsky reminds me of his three-part series on past evidence of the Bradley-Wilder effect. His second post in the series provides some very helpful explanation of why interviewer effects are an important clue:

They key to understanding the Bradley effect from this point of view is to think about who would be uncomfortable answering the candidate preference question. For this, we need to put each election in its proper context. The 1989 New York City mayoral election is the case I'm most familiar with, both because I've done some analysis of the pre-election polling data, and because I was a New York resident at the time. In that election the preferred candidate of older Jewish Democrats (or, as I like to call them, Mom and Dad*), Ed Koch, lost a contentious Democratic primary to David Dinkins, who is black. Considering that many older Jewish Democrats had never in their life voted for a Republican candidate, a vote for Giuliani in the general election could be seen as nothing but a vote against Dinkins. Indeed among Jews over 50, 30 percent claimed that they didn't know who they were going to vote for a week before the election, even though 93 percent said they would definitely cast a vote (among non-Jews under 50, 7 percent said they didn't know who they were going to vote for and 89 percent said they would definitely vote). These are the precise circumstances where we would expect to see the polls perform poorly - and they did.

The whole series is worth reading in full.



Has any of these polls taken into effect racial attitudes today vs. what they were 20 years ago? The amount of people who will vote based on this so-called Bradley effect may only be a fraction of what it was 20 years ago, if that. If anything, there may be more a a reverse Bradley effect. Also, what about the number of new voters that the Obama campaign has factored into this equation? Has that been considered?


Because Obama is half-white, his 6% Bradley effect will be only 3%.

What's Sarah up to now???



I think the Bradley effect was created so that the MSM can hedge their bets/reporting when it comes to inter racial elections. That way they will never say they are right, and never say they wont be wrong.

When Florida was up for Kerry in 04 in polls before the election and exit polls did they blame it on that people dont like to admit they'll vote for a Democrat?

One more point, isn't it true that there was a controversial ballot initiative on the California ballot during the Bradley Gubanatorial election that may have effected turnout.



Langer's evidence strikes me as very important for the following reason:

The way I have seen this conversation typically play out, people note that recent contests have shown no evidence of a Bradley effect. The typical reply is that this is the first relevant Presidential election, so maybe that recent evidence isn't applicable.

Now for several reasons I think that isn't a great reply, but in any event Langer's evidence is evidence about this very contest, so can't be disregarded on those grounds. That said, I suspect it won't really stop the chatter, because in the end too many people have an interest in seeing the Bradley effect arise in this contest.



My theory about the Bradley effect is:

1. When a black candidate is a novelty for a particular job, whether mayor, senator or President then he/she naturally attracts not just black voters from his/her own party but pretty well sweeps the board of black voters.

2. However what this does is to make the demographic sample of undecided voters distinctly untypical. In many states with a substantial AA population you would be left with an almost entirely white demographic amongst the undecideds.

3. In a blow out this would not matter but in a close race against a white candidate the race would only be close if the white candidate was taking a clear majority of white voters.

4. Thus the undecideds, if they simply mirror the rest of the white population, will break mainly for the white candidate. In extreme cases the polls will show the black candidate at the ceiling of his vote and all of the undecideds will go for his/her opponent.

This is not racism, nor is it people lying to pollsters. It is just the way things work.

In later years, when black candidates are no longer such a novelty, black voters will split more along traditionally Dem/Rep lines and the 'Bradley effect' naturally disappears. There will naturally be a 'normal' percentage of AA voters who are undecided up to the end.

As far as Obama/McCain is concerned I think we will see a split this time. In predominantly white states we will likely see the final polls give a good guide to the final outcome. But in states with large black populations Obama might not pick up many undecided voters.



What are the comparisons between the current election campaign in the US of A and the election in the UK where Kinnock was predicted to win big against John Major?

What lessons were learnt from that particular election?




One lesson I have seen discussed is faulty voter recall. It seems that the pollsters sampled too many Labour (Kinnock) voters and not enough Major (Conservative) voters.

Some pollsters tried to weasel out of it by blaming the voters for being 'shy conservatives' i.e. not wishing to admit to supporting an apparently unpopular government.

A better explanation was that pollsters were too reliant on voters memory of who they voted for in the previous election. It seems those who said they voted conservative the last time was nothing like the true percentage (or so the pollsters claimed) so the pollsters got their samples wrong.

There is a lot riding on the pollsters in this election getting their demographics and party ID's right. Probably more than in any other election it is going to be critical as to how many people really identify Dem or Rep, how many young voters turn up, whether AA turnout really is larger than ever before etc.

And of course another factor recently coming up on the radar is how many registered voters are real people and how many were invented or re-registered by canvassers in order to get paid?


Kevin Hayden:

I heard an interesting take on the Bradley/Wilder effect.

It doesn't show up in people polled as for the black candidate, the difference from those for Bradley/Wilder in the last poll and the result was statistically insignificant. They got only the votes they were said to have, no more and no less.

The "effect" shows up in the "undecided" voter, they tend to vote for the white candidate.

So, while the margin compresses, what the black candidate has in poll numbers is what he will have. So, if polls show Obama with 52% in a state, he will likely win that state. If he has anything less than 50%, he will likely lose the state.



Your theory may be correct but it has a major factual flaw. It assume there is a great deal of diversity in the black vote in most elections. This is simply not the case historically. Many assume that Obama has 95% of the Black vote because he is Black but remember Kerry got about 90% of the Black vote as well. Black Americans are the most partisan voting group in American and this has been true through out the nations history. However I do think your conclusion of the polling will be correct just not for the reasons you stated.


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