In this bonus podcast Sky's Head of Data Harry Carr talks to the man behind YouGov's 'multilevel regression and post-stratification' model which successfully predicted a hung parliament at the 2017 general election. Ben Lauderdale - who's an associate professor at the department of methodology at the London School of Economics and Political Science - explains the methods behind MRP and how it's helped restore faith in opinion polling following a difficult few years. #GE2017 #skynews #polling