Monday, August 23, 2010

RBA undergoes significant modifications

RBA entered the TFG rotation near the middle of last season and lacked polish.  Justin's TFG algorithm has been going strong for about three years, so it's no real surprise that it kicked my tail near the end of the season.  However, RBA is coming back with a series of improvements for 2010.

  1. Cross-season historical data:  Last season, RBA did not consider history from previous seasons.  In 2010, RBA will maintain history across seasons to better identify historically strong programs and historically weak programs.
  2. Weighted least squares interpolation:  RBA used the least squares algorithm to estimate offensive and defensive efficiency as a function of team strength.  With the incorporation of historical data, RBA uses a weighted least squares algorithm.  The weight is computed as w^k, where 0 < w < 1 and k is the number of weeks since the game took place.  This allows RBA to naturally filter out older games in favor of newer ones.
  3. Dropped penalties and turnovers:  Last year's algorithm was a deliberate departure from Justin's TFG algorithm because I wanted to explore different approaches to predicting football games.  Analysis indicated that these metrics didn't really add a lot to the accuracy.  In fact, over the course of over 3500 games, they only improved RBA's prediction accuracy by a whopping three picks.  The leading hypothesis is that penalties and turnovers effectively "double count" efficiency.
  4. Drastically improved run-time:  RBA's performance is now six times faster than 2009's version.  This doesn't mean a lot for the output, but it allows for significantly faster iteration.  Indirectly, this improves RBA's accuracy because it allows me to experiment much more quickly and tune the algorithm more easily.
All these changes add up to nearly 2% improvement.  Since 2003, RBA is now up to 71.9% accurate from 70.2%.  It's not quite Justin's 74%, but it's getting there.

Wednesday, August 4, 2010

Sad News

This blog is closely tied to Fark, in that we use the Fark Sports tab as a place for discussion, to get feedback about our rankings -- usually in the form of, "you're an idiot for thinking Oklahoma is that good" -- and because both of us are members of Fark.

Yesterday afternoon Fark lost one of its cornerstones, Nasser Kashani. He had been fighting an undiagnosed medical issue for several months and finally lost that battle. Nasser was the ultimate sports fan, following NASCAR, hockey, football, baseball, wrestling, and (to a lesser extent) basketball. He was a die-hard Blackhawks fan, and spared no expense in celebrating their capture of Lord Stanley's Cup this year. He was a constant presence in the NASCAR, hockey, and football threads. He had (with an unknown level of seriousness) committed to participating in our upcoming college bowl pick'em, and I was really looking forward to talking trash with him in those threads. He was a graduate of Purdue and loved all things Boilermaker and Big 10 related.

Beyond that, he was a great guy and a good friend to an amazing number of people. I didn't know him as well as many other members of Fark, but in all our discussions and debates he was often snarky and competitive but never mean. He took more crap and snark than he ever dished out, but he never seemed to let anything get to him. His memorial thread on Fark shows the degree to which he touched so many lives; the outpouring of grief reflects a man who always had a minute for his friends, started every day with a "Good morning, sunshines", and finished conversations with a kind word. He stands as one of the top contributors to Fark, and in a concrete way he helped shape the tone of the forum and the community that exists there.

This past April he organized and pulled off the head-and-shoulders-above-the-competition Best Fark Party Ever(TM). Well over a hundred people from across the country descended on Chicago for a weekend of drinking, partying, and hanging out. People who only knew each other as screen names on a web forum spent massive amounts of money and time to drive, fly, or take the train to what everyone knew was going to be The Event of the Year. Nasser cajoled, pleased, begged, and even ordered people to show up. Partially this was to say that he himself had organized the greatest Fark party ever -- something he took great delight in pointing out -- but partially because he just loved seeing people get together and have a great time. In recent weeks, even as illness confined him to the hospital and eventually the ICU, he continued planning a follow-up party to be held in Vegas this spring.

Always the optimist, his last message to the outside world was one to comfort a worried friend.

Nasser was 29, and leaves behind his parents and a brother.