WA Marriage Polling Remains Strong
breaks down the Bradley Effect issue:
But what about the so-called "Bradley Effect" in which survey respondents are known to mislead pollsters on certain issues and candidates due to a "social desirability bias" (i.e. they don't want to appear prejudiced against, say, gay or black people)? For example, in 2009 the Washington Poll predicted that R-71 (domestic partnerships) would pass by a 17-point margin. It actually passed by only 6.3 points. Pollster Matt Barreto attempted to adjust for this by asking two further questions: Did you give any answers that weren't 100 percent honest, and were there any questions that made you uncomfortable? Respondents who answered that they may have lied, and that they were uncomfortable with the marriage equality question, but who reported that they were leaning Yes on R-74, were undecided, or would not vote, were moved into the No column, as were lean-yes voters who answered a series of questions defining them as very religious conservatives. The result: An estimated 52.9 to 46.6 margin in favor of R-74 among likely voters, a 6.3 point difference.