National polls and how they can be wrong.

[safeinOhio]

from the National Post

As the results began streaming in from the last polls in British Columbia, it became apparent that Liberal leader Justin Trudeau, whose father Pierre was one of Canada’s most legendary leaders, had exceeded the 170-seat threshold for a majority government that even the most recent polls indicated would be impossible.

[Erich Bloodaxe BSN]

1. The 'how' seems to be missing.

I'd say the 'how' lies in voter prediction models that don't match the actual voters who go to the polls. Every pollster looks at past data to try and predict the 'balance' of how many folks of each party, or indeed each ideology, will actually get out and vote. And for your generic elections, those tend to work well enough. Where they fall down is in 'weird' elections, when the general populace isn't behaving as they normally do. Then pollsters have to decide if they'll stick with the modeling that's worked for them forever, or try and guess how the zeitgeist will change the balance of who actually votes.

I think we've gotten to a point where even calling people on phones isn't necessarily accurately representing the voting public. A lot of people simply blow off phone calls from numbers they don't know. So your polling data comes from the sort of people who are more willing to answer odd numbers, or who WANT to participate in polls if the caller ID actually shows it's a pollster.

[Fumesucker]

2. This goes along with an OP I put up a few days ago..

http://www.democraticunderground.com/1251669554

Data-driven analysis is only as good as the categories by which you sift the information. If you’ve already decided that “liberals” are the people who prefer locally sourced arugula to eating at McDonald’s, or are the people who don’t watch Fox News, it is a reasonable conclusion that there aren’t enough “liberals” out there to elect Bernie Sanders. Yet political categories shift. One of the things the best politicians do is work to shift them.