Why opinion polls doesn't say it all

Why didn’t the polls predict Donald Trump's election victory? Richard Öhrvall, IFN and Linköping University, was interviewed in a number of papers answering this question. To Dagens Nyheter he explained that focus of the US election has been on analysis of combinations of opinion polls, rather than individual polls. The incentive to make reliable but more expensive opinion polls has thus been weak. Öhrvall was also interviewed in Metro and Forskning & Framsteg. To the latter, he explained that "the evidence suggests that those with unconventional positions are less inclined to tell about them in the polls."