Explicit vs. implicit data for news personalization

A paper at the upcoming WWW 2007 conference, "Open User Profiles for Adaptive News Systems: Help or Harm?" (PDF), concludes that allowing users to edit profiles used for news personalization can result in worse personalization.

From the paper:

Despite our expectations, our study didn't confirm that the ability to view and edit user profiles of interest in a personalized news system is beneficial to the user. On the contrary, it demonstrated that this ability has to be used with caution.

Our data demonstrated that all objective performance parameters are lower on average for the experimental system. It includes system recommendation performance as well as precision and recall of information collected in the user reports.

Moreover, we found a negative correlation between the system performance for an individual user and the amount of user model changes done by this user. While the performance data vary between users and topics, the general trend is clear – the more changes are done, the larger harm is done to the system recommendation performance.

The results of our study confirmed the controversial results of Waern's study: the ability to change established user profiles typically harms system and user performance.

The paper was not clear on exactly why editing the profiles made the personalization worse, but I would look to what Jason Fry at the Wall Street Journal wrote several months back:

When it comes to describing us as customers and consumers, recommendation engines may do the job better than we would.

In other words, we lie -- and never more effectively than when we're lying to ourselves ... I fancy myself a reader of contemporary literature and history books, but I mostly buy "Star Wars" novels and "Curious George" books for my kid.

As I wrote after seeing Jason's article, "Implicit data like purchases may be noisy, but it also can be more accurate. You may say you want to watch academy award winners, but you really want to watch South Park. You may say you want to read Hemingway, but you really want to read User Friendly."

See also an April 2004 post where I said, "When you rely on people to tell you want their interests are, they (1) usually won't bother, (2) if they do bother, they often provide partial information or even lie, and (3) even if they bother, tell the truth, and provide complete information, they usually fail to update their information over time."