tag:blogger.com,1999:blog-30715906944242942322011-04-21T23:42:31.475+02:00GreenCirclehttp://www.blogger.com/profile/16918879794582047838noreply@blogger.comBlogger21100tag:blogger.com,1999:blog-3071590694424294232.post-41858071774467655572008-12-28T14:38:00.002+01:002008-12-28T14:44:47.793+01:00<span class="Apple-style-span" style="font-family: arial;">Yahoo! After the submit on December 26th 2008 that put me on position 42, today (December 28th 2008) I made it into the top 40. With a new (and simple) postprocessor that accounts for a bias a user may have on a specific day I got the score down to 0.8755 which ranks me at position 36! Only one small disappointment... the improvement over the Cinematch score is 7.98%. Next step is to got over 8%... shouldn't be to hard since there is still plenty of room for improvements. Just have to wait another 24 hours before I can submit again...</span><div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3071590694424294232-4185807177446765557?l=wmestrom.blogspot.com' alt='' /></div>GreenCirclehttp://www.blogger.com/profile/16918879794582047838noreply@blogger.com0tag:blogger.com,1999:blog-3071590694424294232.post-35527208273040736022008-12-09T20:14:00.004+01:002008-12-26T16:06:42.122+01:00<div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;">Hi, this is a little blog about team GreenCircle in the Netflix prize competition. My name is Willem Mestrom and I am the sole member of team GreenCircle. In May 2008 I first read some things about this competition. Since I am a mathematician and informatician I figured it would be nice to see if I could compete, team GreenCircle was born.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;"><br /></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;">Since then I have learned an awful lot about collaborative filtering. From different matrix factorization techniques and Restricted Boltzmann Machines to asymmetric factoring and some really fancy nearest neighbor techniques.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;"><br /></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;">Putting all of this new knowledge into a computer program and optimizing it so it can be used on a huge dataset like the netflix dataset proved interesting. Even though this is pretty close to the kind of things I had to do at the university when I was studying it is still no easy task to manage so many datapoints in an efficient way.</span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;"><br /></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="font-family: verdana;">November 7th 2008 I finally got to a point where I had a nice prediction set to submit to Netflix. It came back with an RMSE of 0.8909. A very nice result for a first submittion. In the next weeks I submitted a few more sets making big steps towards a nice ranking on the <a href="http://www.netflixprize.com//leaderboard?limit=50">leaderboard</a>. Today, December 26th 2008 I reached a score of 0.8773 (at this time ranking me at position 42). Just short of the top 40 which is displayed by default. But with quiet a few ideas for improvements still on my desk I'm sure I will be in the top 40 really soon...</span></div><div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3071590694424294232-3552720827304073602?l=wmestrom.blogspot.com' alt='' /></div>GreenCirclehttp://www.blogger.com/profile/16918879794582047838noreply@blogger.com0