Imagine I have set up a completely new political party and in my manifesto I tell my followers not to trust the polls and to slam down the phone on any polling company that tried to call and not answer any surveys.
My party is now effectively invisible to researchers!
How does a polling company work out how many followers this new party has?
Could this phenomenon go to explain the massive miss read in the US election polls?
...Trump painted polling companies as the enemy, it is no wonder some of his followers as results might have refused to engage with them and as a result the polls end up with a hole in their numbers.