Wednesday, July 1, 2009

The End Is Near

The end Netflix Prize is near: BPC has reached 10%.

Now, how do I apply what I've learning during the participation of this contest ? Maybe I should get into trying to predict the stock market or commodity prices, or something. People are already doing that on the stock market, it's called algorithmic trading.

Of course recommender systems and data-mining can be applied to all kinds of products and services, not just movies. For example truck dealers can try to find people who are most likely to buy trucks and send them truck advertisement; online matchmaking services can match people based on user data and history of matches.

Of course, for most products and service there are obvious "indicators" that we all know. For example, males in construction industry are probably far more likely to buy trucks than people in general. But still, there might be some subtle indicators and trends that can only be discovered by a computer algorithm, which might improve the accuracy of recommendations by 10%, as measured by RMSE. And as BellKor's research shows, even a few percentages of RMSE improvement can translate into huge increase in the quality of the recommendations you get. You'll actually like the products recommended to you, or the people.

How Can It Work For Matchmaking ?

Well, now I think about it, it probably won't work for matchmaking services. Why ? Because for matchmaking services, it will take a long time to truly know the quality of the recommendations.

Sure, you can find out about bad ones pretty soon: people go on one date and can't stand each other. But how do you know which recommendations are really good, and which ones only look good now but will end up in messy divorce 10 year later ? I think for matchmaking services, you'll have to wait for a generation to tell which recommendations are truly good. But by that time, society and people in general would have chance a lot, so whatever worked 20 years ago probably won't work so well today.

So for matchmaking services, the value of recommender systems is probably to filter out potential incompatible dates.

2 comments:

Larry said...

Please explain what you mean by BellKor's "huge increase in the quality of the recommendations"? Some don't share that same enthusiasm.

http://mat.tepper.cmu.edu/blog/?p=174

Anonymous said...

Larry,

I'm not sure who are those that "don't share that same enthusiasm", and what their expertise in the matter is.

However, to get a more scientific insight ino this, try BellKor's reported experiments in: http://public.research.att.com/~volinsky/netflix/kdd08koren.pdf