And the direction of the error was known and stated in advance by informed interpreters (538). A fair number of Trump voters would not have been considered “likely” voters based on past non-voting, and that was a systematic bias in the polling estimate rather than something that would affect a few states independently. Pollsters tended to stick with their “likely” filter rather than change it on the assumption that these voters would turn out and vote. They turned out and voted.
I seem to recall seeing Trump doing better in polls of registered voters versus likely voters, but I cannot say I have strong evidence for that and it might have just been comparing a few surveys. Most polls seem to have been of likely voters.
And the direction of the error was known and stated in advance by informed interpreters (538). A fair number of Trump voters would not have been considered “likely” voters based on past non-voting, and that was a systematic bias in the polling estimate rather than something that would affect a few states independently. Pollsters tended to stick with their “likely” filter rather than change it on the assumption that these voters would turn out and vote. They turned out and voted.
I seem to recall seeing Trump doing better in polls of registered voters versus likely voters, but I cannot say I have strong evidence for that and it might have just been comparing a few surveys. Most polls seem to have been of likely voters.