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Within The Margin Of Error: How Polling Really Works

With the midterm elections just a few months away, each new week will bring a new poll breaking down the campaigns. CBS News Director of Elections and Surveys Anthony Salvanto joins us to talk about how this data is collected – and about what happens when the numbers don’t predict the winner. His new book is called “Where Did You Get This Number? A Pollster’s Guide to Making Sense of the World” (Simon & Schuster).