This column appeared before the conventions but cogently explains the fault lines of polling….rsk
Gabriel Sanchez is Professor of Political Science and Executive Director of the Robert Wood Johnson Foundation Center for Health Policy at the University of New Mexico. He is also a Principal at the research and polling firm Latino Decisions.
Alan Abramowitz is the Alben W. Barkley Professor of Political Science at Emory University
In 2012, national polls in October suggested the presidential race was a virtual tie. The Real Clear Politics polling average gave Barack Obama a slight 0.7 point lead over Mitt Romney, but he actually won by almost 4 points. Of the final 11 national polls released in 2012, as reported on Real Clear Politics, 7 were a tie or had Romney ahead, while only 4 had Obama ahead.
Why were so many of the polls wrong? In part, because they failed to capture how minorities would vote. Unfortunately, some pollsters may be making the same mistakes in 2016 — and thereby underestimating Hillary Clinton’s lead in the polls.
In 2012, many polls underestimated how many minorities would vote and how many would vote for Obama. For example, a Politico poll released the morning of Election Day said the race was tied at 47 percent each for Obama and Romney. The poll said that 62 percent of Latinos supported Obama, while the exit polls reported 71 percent, and Latino Decisions reported 75 percent. Among the “another race” category, which is mostly comprised of Asian Americans, Politico reported that 47 percent supported Obama, while the exit polls reported 73 percent, and an Asian American Decisions exit poll reported 72 percent.
And Politico was not alone. A Monmouth/Survey USA poll, which had Romney leading by 3 points, suggested that Obama would barely win Latinos, 48 percent to 42 percent.
This problem was known before election day. In the fall of 2012, Mark Blumenthal asked “Is The Gallup Poll Favoring Mitt Romney By Undersampling Minority Voters?” which came after a series of blog posts by Alan Abramowitz, one of which asked “Is Gallup Heading for Another Big Miss?” As Nate Cohn has recently pointed out, it is difficult to know the “correct” percent of voters that are white vs. non-white. Nevertheless, many 2012 polls underestimated Obama’s share of the vote by under-representing minorities’ share of the electorate and underestimating their support for Obama.
Now, in 2016, it looks like many pollsters didn’t learn much from 2012.
Several polls suffer from flaws in how they sample Latinos. While large bilingual polls of Latino voters from outlets such as Latino Decisions and Univision/Washington Post have reported very little support for Donald Trump, other national polls that interview Latinos only in English show that 29 percent to 37 percent of Latinos will support Trump — better even than Romney fared. These polls also show Trump doing as well or better among Asian-Americans, compared to Romney. Some polls even estimate that 20 percent to 25 percent of blacks support Trump.
Here is one example from a Survey USA poll conducted on behalf of The Guardian, which gave Clinton a 3-point lead over Trump (39 percent vs. 36 percent). The sample of the poll was 74 percent white. However, a comprehensive analysis of census data and growth rates by Ruy Teixeira and William Frey estimates that less than 70 percentgof voters in the 2016 cycle will be white. If we adjust the racial composition of this poll to reflect the Teixeira and Frey’s estimates, Clinton’s margin grows to almost 5 points (see here).
The Survey USA poll is also arguably underestimating support for Hillary Clinton among three different groups of minority voters:
•Asian-Americans. In this poll, Clinton leads 48-29 among Asian-Americans. However, a recent national survey of Asian American registered voters conducted in six different languages found that just 10 percent planned to vote for Donald Trump.
