Cross-posted from Mark the Ballot:
A couple of days ago I made the following statement:
I must admit that the under-dispersion of the recent polls troubles me a little. If the polls were normally distributed, I would expect to see poll results outside of this one-point spread for each side. Because there is under-dispersion, I have wondered about the likelihood of a polling failure (in either direction). Has the under-dispersion come about randomly (unlikely but not impossible). Or is it an artefact of some process, such as online polling? Herding? Pollster self-censorship? Or some other process I have not identified?
