NCAA Tournament — Seeding
All of the analysis is only looking at the 64 team field from the 1985 tournament through 2013. Before 1985 there were less than 64 teams invited. Opening Round games are also ignored.
The NCAA Selection Committee just released the seeding for the upcoming tournament, and everyone over the next few days will be filling out brackets to win 50$ from their office pool. But who to pick? Later this week, I’m going to look at a basic way to predict the point spread for an NCAA tournament game. Before I look at that prediction, let’s examine how the different seeds perform in the tournament.
Seeds are ordinal ranks (1 through 16) placed on the 64 teams and then those teams are pitted against each so the highest seeds won’t face each other till the final round in the Regional Championship (Elite Eight). So how well do the seeds perform? The graphs above show how well each seed has done since 1985, the first year of the 64 team bracket. The 1 seeds are clearly are the most successful in any around, and beyond that there’s a linear pattern with first round wins. So the better the seed the more likely the team is to go further.
In fact the likelihood of the highest seed winning the first game goes from 100% for the 1-16 game to a coin-flip for the 8-9 game.
Looking at the first round wins, there are two interesting seeds, the 9 and 12 seeds, which outperform the pattern. This most likely happens because the Selection Committee undervalues teams it assigns to those slots. There’s an asymmetry of information available for power conferences vs mid-majors. Mid-majors have less games against top 50 teams, so the the committee has less information to judge the team.
Now as far as selecting teams to win tournament games. The safest pick is to always pick the highest seed. The argument against this is that its very boring and you might not win. Being the most likely to win does not really translate into winning in singular instances. But the data points to 1 seeds being the overwhelming favorite to get into the Final Four over any other particular seed by a 2:1 margin.
Picking upsets. The underlying principle of the upset in this tournament is the small sample size of just one game. A lot can happen in one game. Even if a team has a 78% chance of winning, which is rather favorable (Like a 4 seed)….there’s still a 22% chance that team will lose. With 64 teams and 63 games there’s a lot of room for upsets to happen by random chance. The randomness is in how the team feels that day, how fouls are called, if a foul was called in a critical junction, or come down to how a ball bounces or falls.
Given the way the seeds have performed since the tournament expanded in 1985 to a 64-team tournament. The selection committee does a good job seeding the teams, since they are following a pattern you would except from seeding the best teams against the worst.