The question of how Billboard determines the most popular music in the country has gotten a lot harder in the digital age. It used to be a simple question of which album sold the most physical copies, but now Billboard needs to consider things like Spotify plays and mp3 downloads. Starting Jan. 3, it will also include YouTube streams.
NPR's Ailsa Chang talks to Chris Molanphy, a chart analyst and pop critic at Slate, about the significance of this change. Listen at the audio link and read on for an edited version of their conversation.