I remember when the Netflix prize was underway, there were certain movies—Napoleon Dynamite was one of them specifically—where it was incredibly difficult to de

I remember when the Netflix prize was underway, there were certain movies—Napoleon Dynamite was one of them specifically—where it was incredibly difficult to determine if someone would enjoy it based on their other ratings. And yet it was also enormously popular, so lots of people ended up reviewing it. Honestly, read up on the articles discussing the Netflix prize, they tended to mention a lot of unexpected gotchas. For instance, it turns out, ratings aren’t really independent. If you rate something good, it will affect how you rate the next thing. Stuff like that.