Why did it appear that California's Proposition 8, which banned same-sex marriage, seemed to be going down to defeat and yet was approved by voters?
To answer this question, we must first examine the trend of voter preferences on Prop. 8 as reported by The Field Poll and the Public Policy Institute of California (PPIC), the two leading polling organizations in California. Field and PPIC conducted six separate samplings on Prop. 8 between July and late October. In each, Prop. 8 were trailing, albeit by declining margins as Election Day approached.
Some have posited that one reason for the disparity between the run-up to Election Day and the final outcome is that some survey respondents were lying to the pollsters. In their view, some portion of those who voted yes felt compelled during their pre-election interview to disguise their support for the initiative. It is a theory without any supporting evidence.
There is a far more compelling explanation for the variance that is corroborated by the evidence.
First, polls are a snapshot in time and the trend of the pre-election polls clearly showed the "no" side's advantage declining in the final weeks. Double-digit leads held by the "no" side in the pre-television advertising stages of the campaign declined precipitously as the TV ad campaigns hit in mid-to-late-September. This suggests that the "yes" campaign advertising was having its effect.
This drift in voter preferences away from the "no" side must have continued into and through the final weekend of the election as the churches and various religious groups made their pitches to rally the support of their congregations for a "yes" vote. There is evidence that their efforts succeeded. When comparing the findings from The Field Poll's final pre-election survey to the Edison Media Research exit poll of voters, the biggest differences related to the turnout and preferences of frequent church-goers and Catholics.
The Field Poll, completed one week...