Polls: Not to be believed except when they are to be believed

The politics of polling
Intergovernmental Affairs Peter Penashue, MP for Labrador, addresses a news conference in Happy Valley-Goose Bay, Newfoundland and Labrador, Nov. 30, 2012. Penashue has resigned his seat in the House of Commons and says he’ll run again in Labrador in an effort to clear the air over election funding irregularities. THE CANADIAN PRESS/Andrew Vaughan

Monday night: the difference between earlier public polling and the election result demonstrates that Justin Trudeau is in over his head.

Tuesday night: the difference between public polling and the election result demonstrates that polls are not to be given much credence.

Actually, Forum Research’s last poll in Labrador was fairly reflective of the final vote—and Conservatives could point to that as evidence of Mr. Trudeau driving voters away, but then the 20-point drop they claimed on Monday night becomes a nine-point drop (from 57% in early April to 48% on by-election night).