Most of the polling for the 2016 US presidential election have been favourable to Hillary Clinton. One of the biggest questions I have right now is whether the polling is accurate. In particular, whether people are hiding the fact they intend to vote for Trump when polled for it. Have pollsters examined the possibility of a shy Tory factor / Bradley effect and seen whether it's affecting polling numbers for this election campaign? What have they concluded?
But James Lee of Susquehanna Polling & Research Inc. said his firm combined live-interview and automated-dialer calls, and Trump did better when voters were sharing their voting intention with a recorded voice rather than a live one.
This is a variant of the Shy Tory or Bradley effect. Of course, it could also be caused by other things. For example, live-interview may include cell phones and Clinton voters may be younger and more likely to use cell phones.
Note that immediately before that they said:
Several pollsters rejected the idea that Trump voters were too shy to tells pollsters whom they were supporting.
So we don't actually know if this is true or not. Professionals differ on their interpretation of the data.
It's also worth noting that the final popular vote result seems to have been within 1% of the polling. In early returns (when this question was posted), the results were farther away. That said, there were still some notable polling misses, e.g. in Wisconsin, where the final result differed from the polls by more than the margin of error in all polls.
All polls take this into account. I don't have any english source, I saw this in lessons of a french politics university. It has been applied for at least the last 25 years. There is a factor which is actualised at each election. It looks very surprising since it is never mentioned in the media, and it looks odd to be shy in an anonymous poll. But it is true.
If you want english sources, I suggest you look into politics courses. It is quite hard to find, if someone has something, please post it in comment.