The Bradley Effect is quite often mentioned in the media as we approach the Presidential election. It refers to the under-performance of a black candidate as compared to poll numbers. A good summary of various issues can be found here. A lot of the information about this effect is speculative or based on sparse polling numbers from other races which have led to questions of whether the effect really existed, whether it was seen in other races and whether in 2008 it is still likely to be seen. Perhaps the best study on this issue was conducted by Anthony Greenwald and Bethany Albertson the University of Washington. They used data from the Clinton-Obama primary, the most comprehensive source available and studied it using regression analysis to explore the existence of the Bradley effect.