There’s been lots of discussion but little actual research on the so-called Bradley effect. David Stromberg, an economics professor at the University of Stockholm and Princeton economics Ph.D. takes a detailed look at 431 elections for House, Senate, and Governor over the 1998-2006 period involving 26 black candidates – 17 Democrats and nine Republicans. He finds that the Bradley effect in the election will be closer than many Obama supporters think and polls indicate, but that Obama should still prevail.

Should Barack Obama worry about the Bradley effect? The much-discussed effect refers to observed discrepancies between voter opinion polls and election outcomes, in which African-American candidates receive a smaller vote share than would be predicted using opinion polls. In this column, I study US congressional and gubernatorial contests from 1998 to 2006 – black candidates on average receive a 2-3% lower share of the two-party vote than non-black candidates with similar numbers in the polls. If an effect of a similar size would appear in the current presidential race, then it would lower Obama’s probability of winning from 85% to 53%. However, black Republican candidates drive the result, so it may not apply to Obama’s campaign.

The full article is here.