Are Survey Respondents Lying about Their Support for Same-Sex Marriage? Lessons from a List Experiment

Public opinion polls consistently show that a growing majority of Americans support same-sex marriage. Critics, however, raise the possibility that these polls are plagued by social desirability bias, and thereby may overstate public support for gay and lesbian rights. We test this proposition using a list experiment embedded in the 2013 Cooperative Congressional Election Study. List experiments afford respondents an anonymity that allows them to provide more truthful answers to potentially sensitive survey items. Our experiment finds no evidence that social desirability is affecting overall survey results. If there is social desirability in polling on same-sex marriage, it pushes in both directions. Indeed, our efforts provide new evidence that a national opinion majority favors same-sex marriage. To evaluate the robustness of our findings, we analyze a second list experiment, this one focusing on the inclusion of sexual orientation in employment nondiscrimination laws. Again, we find no overall evidence of bias.