Opposition to same-sex marriage is greater on Election Day than indicated in pre-election polls, according to new research by a University of Maine political scientist. That’s because people being surveyed tend to say they’ll vote the way they think is socially desirable, regardless of their real position on the issue.
Richard Powell, UMaine associate professor of political science, said polling systematically minimizes resistance to same-sex marriage; opposition to it at the ballot box on Election Day is about 5 percent to 7 percent greater than in pre-election polls.
The 2009 vote in Maine is indicative of this pattern, Powell says. In that year’s final pre-election poll, 40 percent of Maine voters indicated they would vote in favor of Question 1 to restrict marriages to opposite-sex couples. Election Day, Question 1 passed with 53 percent of the vote.
Powell examined the accuracy of polling on same-sex marriage ballot measures relative to polling on other statewide ballot issues in 33 states from 1998 to 2012.
He said social desirability bias on ballot measures such as same-sex marriage is more prevalent in states with larger populations of Republican and highly religious voters.
While social desirability bias has largely disappeared on issues of race and gender, Powell says it likely continues to impact polling on same-sex marriage because societal attitudes with regard to homosexual rights lags behind that of attitudes about race and gender.
Based on prior research, Powell says as a greater number of people accept same-sex marriage, there will be fewer potential polling respondents available to give misleading responses.
“This is a question that will be fascinating to study over time to see if it, indeed, turns out to be the case,” he writes in “Social Desirability Bias in Polling on Same-Sex Marriage Ballot Measures” published in American Politics Research.
Contact: Beth Staples, 207.581.3777