If you are still mulling over the British Columbia election result and the polls, take a look at this post by Eric Grenier at threehundredeight.com. It includes a link to his piece in the Globe on Wednesday on the same topic.
Pollsters tend to weight their samples to match the population as a whole. Problem: that isn’t the same as the demographic profile of voters.voters.
Grenier shows how Ipsos, for example, weighted a poll equally across three age groupings. In the 2013 election, those age groupings didn’t turn out equally. The over-55s made up half the total voter turn-out, not one third.