After I wrote about the issues I had with Netflix recommendations last week, I started seeing the same issue in other places. Namely, YouTube and Amazon.

Both services have the same issue as Netflix – suggesting items that have already been watched (YouTube) or purchased (Amazon). Amazon even thinks that I want to buy other editions of books I’ve purchased.

Recommendations seem like a fundamental way to get people to do more (watching, buying, etc). I’m surprised that it’s so difficult to filter out stuff already viewed/purchased.