There’s been a resurgence of talk about ‘The Bradley Effect’ now that Barack Obama is rounding the corner on this political campaign and chances are looking extremely good for him to be the next President of the United States.

With that, I thought I’d include some history of the the term for those who may be unaware. The definition below is summarized from Wikipedia.

The Bradley effect, asls known as the Wilder effect, is a proposed explanation for observed discrepancies between voter opinion polls and election outcomes in some US government elections where a white candidate and a non-white candidate run against each other.

The effect refers to a supposed tendency on the part of some voters to tell pollsters that they are undecided or likely to vote for a black candidate, and yet, on election day, vote for his or her white opponent. It was named for Tom Bradley, an African-American who lost the 1982 California governor’s race despite being ahead in voter polls going into the elections.

The Bradley effect theorizes that the inaccurate polls were skewed by the phenomenon of social desirability bias. Specifically, some white voters give inaccurate polling responses for fear that, by stating their true preference, they will open themselves to criticism of racial motivation. The reluctance to give accurate polling answers has sometimes extended to post-election exit polls as well. The race of the pollster conducting the interview may factor in to voters’ answers.

Some analysts have dismissed the theory of the Bradley effect, while others argue that it may have existed in past elections, but not in more recent ones. One analysis of 133 senate and gubernatorial elections between 1989 and 2006 suggests that “before 1996, the median gap for black candidates was 3.1 percentage points, while for subsequent years it was -0.3 percentage points.

If you want to know more about this, check out the relatively extensive write-up on Wikipedia.