The CBC Pollcast, hosted by CBC poll analyst and founder Éric Grenier, explores the world of political polls and the trends they reveal.

Joining Éric on today's podcast is Susan Delacourt of the Toronto Star and iPolitics and Christian Bourque, executive vice-president at Léger, to discuss the biggest polling stories of 2015.

How was Rachel Notley's NDP able to overturn 44 years of PC dominance in Alberta, and why weren't the polls believed? What impact did the polls have on Justin Trudeau's Liberal victory in the October federal election? And what is going on with Donald Trump and the U.S. presidential primaries?

You can listen to the full discussion below, or subscribe to The CBC Pollcast and listen to past episodes here.

You can also follow Christian Bourque and Susan Delacourt on Twitter.