Comments on: Social network systems

By: Sumana

Sumana — Thu, 17 Mar 2005 19:28:32 +0000

One way to avoid such problems is to make sure you institute “you may not have thought about this”/out-of-left-field recommendations, and instituting an “indie rock” preference that DOESN’T recommend things that you have probably already heard about and seen or otherwise considered. A recommendation engine for web pages implements these:
http://www.crummy.com/software/UltraGleeper/

By: anonymous

anonymous — Thu, 17 Mar 2005 18:39:48 +0000

People have most certainly thought about these problems. The animating principle is to recommend the movie you have the highest probability of liking, NOT the movie that the greatest raw number of people have seen and liked, with a similar background to you. Otherwise, the most popular movies would get recommended to everyone, with slight changes. If this wasn’t built in, the system wouldn’t work at all.

By: Michael Mouse

Michael Mouse — Thu, 17 Mar 2005 16:25:51 +0000

I’ve designed similar systems. I’m still surprised that they work so well. What if people have strange and idiosyncratic habits? It turns out that most people don’t, or at least, that useful information can come from the aggregate of lots of strange and idiosyncratic habits. You can come up with any number of theoretical objections, but empirically it seems to work well enough to keep the punters happy.
On the particular issue mentioned, I’m convinced that the reason they continue to work is that they are not the only thing governing people’s choices. So, ‘frinstance, Chris will presumably still be getting ideas for movies to watch from friends, advertising, blogs, old-fashioned news media, etc, and will continue to do so as well as Movielens.

By: Tom T.

Tom T. — Thu, 17 Mar 2005 13:04:14 +0000

All else being equal, there shouldn’t be any reason to think that there will be significantly more people who start out by discovering A + B rather than A + C or B + C.
Also, even assuming that C did get excluded by chance from these moviegoers’ initial discovery, people don’t stop at two movies. Those who have seen A + B will now have to go out and discover a third movie on their own. Presumably, they’re just as likely to discover C by chance as they were to have initially discovered B by chance after having seen A.

By: lth

lth — Thu, 17 Mar 2005 11:43:05 +0000

To be honest, I don’t think the people who invent these systems have thought about these effects, and they work exactly as you describe.