Gay Marriage by the Numbers–a guest post by Lynn Vavreck and Ryan Enos

YouGov is in the field each week on Saturday mornings with a nationwide, 1,000-person survey. Today, I’m going to look at the surveys before and after President Obama’s ABC interview during which he came out in support of same-sex marriage.

The interview made news for days — and was the topic of endless speculation about whether black voters would “follow obama” on gay marriage. Others wondered: Why was he doing it? Why now? And, of course, what effect would it have on the 2012 election?

The questions stirring in the journalistic community were intense and the conversation from coast to coast, among those interested in politics, relentless.

And yet – very little of interest has happened to public opinion as a consequence of Obama’s revelation. The week before his announcement, 49% of Americans in the YouGov poll supported gay marriage. The week after — 48%, a change far too small to take seriously. Essentially – opinion in general did not move at all after Obama’s interview.

Pooling all 2011 pre-announcement interviews and comparing them to the one post-announcement survey (so we have 1,427 blacks), support for gay marriage changed not at all – 41% before and 41% after. Because our data are a panel, we can compare people’s opinions in December of 2011 to their opinions during the week in which they were interviewed in 2012 (everyone gets two interviews). When we look at how many people are changing – moving off of their initial position to a different one – we find no change in the number of African Americans moving pre and post announcement. About 12-15% are switching their positions regardless of whether we interview them after Obama’s support of the policy or before. But – and here’s the most interesting tidbit – if you changed your opinion before the announcement, there was a 50-50 change you were moving in either direction. But of those who changed after his announcement, 85% moved toward the more supportive position. While there are very few cases to evaluate in the one week after the interview, the result is still statistically distinguishable from zero.

Now, let’s look at white opinion. Before the interview, 54% of the changers (people moving from their December position on gay marriage) were moving toward support. And after the interview, that share drops to 47% — too small to call it different in statistical terms, but an order of magnitude smaller than the change among blacks! To be clear, most people did not change their opinion after Obama’s support of gay marriage, but among those who did, blacks were far more likely to move toward Obama’s position than were whites.

And here’s one more way race is playing a role: Whites with low levels of racial prejudice were more likely to change their position on gay marriage after the announcement than those with high levels of racial prejudice. This result holds even if we control for other things that might drive a reaction to Obama’s announcement (and positions on gay marriage) like party identification and ideology.

Whites with low-levels of racial prejudice who changed their position after the interview were more likely than those with high-levels of prejudice to move toward supporting Obama’s position. The announcement itself had no effect on the positions of these switchers – it was the combination of the announcement and their level of racial prejudice that motivated the movement.

Lynn Vavreck is associate professor of political science and communication studies at UCLA. Ryan Ennos is assistant professor at Harvard University.