The 2013 NCAA tournament has afforded another experiment on whether the seeding process incorporates much more noise than signal. For those following the tournament, it should come as no surprise that this year offers more confirmation of the suspect seeding process.
I collected scores and seed differences for all 48 games from the first two rounds. Using a common statistical technique (regression analysis), I examined the relationship between seed differences and score differences. Seed differences explain a paltry 6 percent of score differences. When the 1-16 and 2-15 are dropped, this percentage falls to only 3 percent. Even as a predictor of win-loss rather than score, seed differences fare poorly. For many of the games, plucking scores from a lottery hopper would come close to providing as much information on outcomes.
Is seeding really intended to predict score differential? Obviously, not directly. However, seeding reflects a gauge of team’s in-season performance quality – wins and losses adjusted for quality of competition. If this gauge has much meaning to it, better seeds indicating higher quality teams, differences between them should show up in scores. Instead, games with large seed differences wind up close or in upsets and games with narrow seed differences result in some blowouts.
It’s not just the NCAA Selection Committee that struggled with finding meaningful differences between teams. Vegas point spreads, direct estimates of score differences, predicted only about 17 percent of score differences. That’s a stunningly low number given that these spreads incorporate information such as injuries and best guesses about team specific matchups.
The 1 and 2 seeds are still very likely to win their opening round games, but even these games have become much more contested. Based on this year’s tourney, I might amend original suggestion to select seeds 1-4 with everyone else randomly selected to just selecting the 1 seeds and randomizing from there. Yes, that would lead to some seemingly strong teams facing other strong teams in the first round, and weak versus weak, but, that’s already happening. The setup just puts a different face on it.