Bradley Effect Myth Persists

[J. J.]

I think it did occur with both Wilder and Bradley, but perhaps more clearly with Wilder. 

There was some evidence that it did occur in some of the gubernatorial elections in the 2000's, but never as pronounced as it was with Wilder or Bradley.  It was dwindling over time

In some states in 2008, IA, for example, Obama did overpoll, i.e. run well below his polling numbers; absolutely nobody expected it.  Where I was looking for it, PA, it didn't happen.

Something that did seem to happen in 2008, that hasn't been reported too much, is that Obama underpolled in states with high Hispanic populations, that were of Mexican ancestry. 

[J. J.]

the bradley effect:

1. now responsible for the statistical margin of error and/or arbitrarily state-specific

2. happens backwards for mexicans

Iowa was outside of the MOE.  I think that was the most dramatic.  We also had some large states where there was not reliable polling, CA, NY, and TX.  We'll see if he runs ahead of the polls in those states this time.

Something happened in NM, NV, and even AZ.  Obama ran ahead of polling.  I wouldn't call it a Bradley Effect.  People lying to pollsters is a possible reason. 

Like I said, another factor was that it was shrinking over time.

[J. J.]

Of course the results remained the same as in the pre-election polls, because more Blacks compensated the loss of Whites.

This was the point I was trying to make. That there may have been unexpected voters compensating for other "lost" voters - hiding the presence of a possible Bradley effect.

A fairly good paper on it is here:  http://people.iq.harvard.edu/~dhopkins/wilder13.pdf

I do disagree with Hopkins that there is an over-reporting effect of the front runner in Patrick's case.  However, I do agree that it was declining prior to 2008.

I think there are some masking factors:

1.  Disproportional turnout.  You expect group X to represent 10% of the vote cast and it's 13%.  Was Gallup so far off because its model expected a 8% Black turnout and it was actually 10%?

2.  There are not a lot of good polls in some of the states.  Did Obama overpoll with whites in AL or NY?  We don't know because we don't have a large number of good polls from AL or NY just before the election.  Did Obama overpoll with Hispanics in CA or TX?  We don't know for the same reason.

I would be looking to see if Obama underpolls with Hispanics of Mexican ancestry more than I would to see if Obama overpolls in general.