After he was finally disgraced fully enough to resign with some remaining dignity, you couldn't find anybody who admitted to voting for him.
And he had been re-elected to a second term !
- Who does or does not have a phone.
- Who will or won't answer a phone.
- Specific target demographics, under the rubric of "stratified random sampling".
Just a few off the top of my head.
As I'd mentioned upstream, political polling has regular calibration events called "elections", and following those events biases and adjustment factors, most falling out of statistical analysis and correlations, rather than "gut feels", are updated.
The problem for the US seems to be that the biases are accelerating well in advance of those adjustments, as my own poll-vs-vote analysis shows:
Thread: <https://news.ycombinator.com/item?id=42060547>
Most robust analysis / results here: <https://news.ycombinator.com/item?id=42064420>
It is like when your doctor is asking you if you eat fast food — some people will downplay it because they know it is wrong, but do it anyways in a "weak" moment when nobody is looking.
So suddenly in my village where I know everybody 56% voted for the right wing candidate, yet everybody¹ claimed not to do that when asked before or after.
¹: except one or two open Nazis