Monmouth Poll: Clinton +4 in Ohio

[Torie]

The thing is Seriously?, 2012 exit polls and actual polls of likely/registered voters showed there to be more Democrats than Republican in Ohio. Why would Monmouth find there to be more Republicans?

They got a crap underlying sample here. That's my point. There was a lot of massaging to make this thing even workable. I am well aware that the exit poll numbers were in the D+7 or so range. They massaged this poll to D+4. The raw sample was R+4.

Did they massage this poll so that it ended up D+4, or did they do other demographic weights that happened to bring the sample to D+4?  There is a huge, huge methodological difference between those two things.  Obviously, neither is desirable, but with polling response rates what they are these days, demographic weighting is probably becoming more and more pronounced in polls.  That may make it more desirable than declining to re-weigh.

Demographic weighting is industry-standard, not undesirable. Even in the days of 25% response rates, (good) pollsters weighted because of differential turnout among RV subsamples, and unequal selection probabilities within households.

To be clear, I didn't mean to indicate weighting is a bad practice -- it's a necessary one.  I just meant polls would be even better if the phenomena that necessitate weighting didn't exist.  It's undesirable that poll respondents are so unrepresentative, and while weighting is the best solution to fixing that problem, it would be better if the problem didn't exist.

For instance, we can weigh up the sample of 18-to-24 year old white females, but that assumes that we're getting a representative sample of 18-to-24 year old white females, and whatever causes a low proportion of those to respond isn't also causing an unrepresentative sample of those to respond.  (Weighting is the right thing to do in that case, but it can't fix every underlying problem.

edit: A more obvious example - weighting up the Hispanic respondent % will get you a misleading result if you don't give a poll in Spanish, because English-only interviews will result in an unrepresentative sample of Hispanics, and re-weighting on race alone won't fix that

Given all the problems with polling these days, it is amazing that the polls are as accurate as they are. This year will be a big test for them, since past election models might not be replicated in this election, and that is what in part is relied upon to do the weighting.