There's been much talk this year of the Bradley Effect, or the Wilder Effect, or whatever name you want to give to the phenomenon of polls overstating a black candidate's support. It is bound to be one of the things which keeps anxious Democrats up tonight. But, as Harvard's David Hopkins has shown, there is no convincing evidence that this effect still exists.
So, for those left-leaning readers looking for another reason to worry, I submit the Shy Tory Factor. British readers will remember that the pollsters badly overestimated Labour support in the 1992 general election. Even the exit polls got the result wrong: this strongly suggested that Tory voters were either failing to speak to pollsters or lying about their choice. The most widely-accepted explanation for this was that the Conservatives had become 'politically incorrect'.
This is simply my own speculation, backed up by a handful of anecdotes, but it is possible that the same thing is going on in America today. In many (though certainly not all) parts of the country, Barack Obama is the 'politically correct' choice, for a variety of reasons - not just race, but also Bush's abysmal approval ratings and the cultural image of the Republican party. This is certainly something to bear in mind if the exit polls show an Obama lead. They also had Kerry ahead in 2004, and we all know how that turned out.
Get our weekly email