The Netflix Prize
I recommend this great article on the Netflix Prize: a $1M bounty that will be given to whomever can increase the quality of its recommendation engine by 10%. Lots of interesting information; my favorite was:
Interestingly, the Netflix Prize competitors do not know anything about the demographics of the customers whose taste they’re trying to predict. The teams sometimes argue on the discussion board about whether their predictions would be better if they knew that customer No. 465 is, for example, a 23-year-old woman in Arizona. Yet most of the leading teams say that personal information is not very useful, because it’s too crude. As one team pointed out to me, the fact that I’m a 40-year-old West Village resident is not very predictive. There’s little reason to think the other 40-year-old men on my block enjoy the same movies as I do. In contrast, the Netflix data are much more rich in meaning.Broadcast advertisers are obsessed with demographic data, because that's how airtime is identified and sold. But it's a poor and distant cousin to actually knowing about individuals' actions and preferences. Let me phrase it this way: would you rather know someone's age and sex, or would you rather know the last 5 queries they typed into Google?