Bloomberg pollster: Why our poll showed Obama up 13
By J. Ann Selzer,
Bloomberg pollster Ann Selzer, whose poll we dissected Thursday after it showed President Obama leading by a surprisingly large margin of 13 percentage points, has crafted a response to the critiques. Below, we are posting it in full:
When people ask how to make sense out of a bevy of widely varying polls, I say, pick a poll and follow it over time. The trend will tell you something meaningful when you compare the same method, and the same question with the same universe over time. Our Bloomberg National Poll in March, before the Republican nominating contest had concluded, showed Mitt Romney and Barack Obama tied at 47 percent each. In our June poll, released Wednesday morning, we showed a 13-point lead for Barack Obama — 53 percent to 40 percent.
Why does our poll look different from other recent polls? Here are answers to a few theories posited in the last day or so about why our poll might be an outlier.
Did you change your methodology? No. It was the same method, the same question, and the same universe. The poll produced roughly the same demographic make-up as our March poll.
Was this a poll of likely voters or registered voters? One of the problems of comparing one poll to another is each may have its own way of looking at the electorate. We ask how likely respondents are to vote in November and if they say they will definitely vote — the top box on a four-point scale — we define them as likely voters. Seventy-two percent in our current poll pass that screen. Some polls ask if the respondent is registered to vote. That is a larger universe and includes people who know today they have no intention to vote, so we prefer a narrower definition of a likely voter.
Did you load up the front of the questionnaire with questions that would tilt uncertain voters toward Obama and away from Romney? No. Our poll asks the horse race after the right/wrong track question about the nation (which is 2-1 pessimistic), after a question about the most important issues facing the country (unemployment and jobs), after favorable/unfavorable impressions of a number of personalities and institutions, and after presidential job approval on a number of elements (including the economy, job creation, and policies on trade with China — which deliver bad news for the president). The March poll included the questions in the same order as the June poll. We conclude the question order did not manufacture a 13-point lead for Barack Obama.
Did you interview too many younger voters who tend to like Obama more? No. Sixteen percent of likely voters in our poll are age 18 to 29, about the same as in the 2008 election.
What about race? Did you under-represent the white vote? Possibly, but only a little. Our likely voter sample includes 69 percent who are white, 12 percent who are black, 10 percent who are Hispanic, and 5 percent who are some other race. The exit polls for 2008 showed whites to be 74 percent of the electorate, blacks to be 13 percent, Latinos to be 9 percent and other to be 5 percent. Our poll includes a place to capture those who refuse to give an answer (4 percent). If we remove those and repercentage the results, whites grow to 72 percent. This is a contest where race is a strong predictor of vote (the white vote goes for Romney 50 percent to 43 percent and the non-white vote goes for Obama 78 percent to 16 percent). So, is the small difference in race a reason for a 13-point difference overall? It may contribute, but it is not the sole difference.
Too many Democrats? Our poll showed more self-identified Democrats than Republicans, which is in line with both our March poll and other polls. Among likely voters, our spread is 42 percent Democrat (including independents who say they lean toward the Democratic party) and 37 percent Republican (including leaners), with 19 percent saying they are totally independent. That is a plus-5 margin for Democrats compared to a Pew Research average of plus-8 for Democrats. It is not the case we interviewed an extraordinarily large number of Democrats, accounting for a big margin for Barack Obama.
Maybe you had a higher-educated respondent pool and they tend to like Obama. Maybe we did. Of all the theories, this one holds some water. The 2008 exit poll shows 24 percent with a high school education or less, compared to our 20 percent among likely voters; the 2008 electorate had 31 percent with some college, and we had 23 percent. In 2008, 28 percent of voters had a college degree and 17 percent more had some postgraduate education; we had 34 percent with a college degree and 21 percent with some postgraduate exposure. However, in our poll, every education subgroup votes for Obama over Romney.
We played around with the data to test whether our findings would have changed had our education distribution looked more like the 2008 exit poll. By “played around,” I mean we created a 52-cell weight variable accounting for age, race, and education. The presidential contest becomes a 10-point race: 51 percent for Obama and 41 percent for Romney. It is still a double-digit lead for Obama and would likely have created as much stir as our 13-point lead.
In the end. We will soon know whether this poll is, in fact, an outlier. Potentially, this poll caught the electorate when the wind was at Barack Obama’s back for a brief moment in time.