Calculating an album's worldwide sales is tricky, even in the age of bar codes and digital downloads. Music companies and artists have been known to inflate or deflate numbers when needed, especially when crafting promotional language or estimating royalty payments. 

One popular, yet dubious statistic: 100 million. That's how many copies of Michael Jackson's 1982 masterpiece Thriller have been sold, according to Jackson's obituary in the New York Times, Thriller producer Quincy Jones' book, and most recently, a new biography of the King of Pop called Untouchable. 

Music journalist Bill Wyman, who recently reviewed Untouchable for The New Yorker and wrote about the 100 million figure for the magazine's blog, joins us with an alternative count he culled from one very devoted, very stats-obsessed Michael Jackson fan.