Scott Adams suggests that conservatives may be playing a huge practicle joke, on pollsters.
The Bradley Effect suggests much the same.
How big is the effect? Who knoows? Does it exist? The 2016 election says it does.
Read Adams’ book Winning Bigly and couldn’t put it down. Love his humor and easy reading style with no bombast. Available for Trump fans on Kendal ebook for around $4. Best book I’ve read on 2016 campaign with explanations of WHY it happened using examples to prove his theories.