Nate Silver agrees with me that much of that shocking 2% swing can be explained by systematic differences between sample and population: survey respondents included too many Clinton supporters, even after corrections from existing survey adjustments.
In Nate’s words, “Pollsters Probably Didn’t Talk To Enough White Voters Without College Degrees.” Last time we looked carefully at this, my colleagues and I found that pollsters weighted for sex x ethnicity and age x education, but not by ethnicity x education.
I could see that this could be an issue. It goes like this: CONT.
Andrew Gelman, Columbia U.