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  • Writer's picturehenryfarleyjohnson

March Madness 2023: Wide Open

Like millions of unproductive basketball fans, I'll be spending the next few days obsessing over the NCAA Tournament. And in conversations with friends about this year's men's bracket, the same sentiment keeps coming up: "It's wide open."

Great news: we can (sorta) measure this!

Methodology (Not Fun)

To do so, I'm going to pair the venerated Ken Pomeroy's pre-tournament win probabilities with a handy tool economists have used for decades, the Gini coefficient.

The Gini coefficient is a number between 0 and 1 that's designed to measure inequality in a population (when you see a list of countries with the highest/lowest income inequality, the odds are good that it's just a ranking of those countries' Gini coefficients). It's not a perfect metric, but such is life.

In this case, we're treating probability of winning the championship like dollars. A perfectly equal distribution would give every team an identical chance of winning the tournament, while a perfectly unequal distribution would give one team a 100% chance and the rest 0%.

One small detail is that a Gini coefficient is higher when there's more inequality, so I'm going to use 1 minus the Gini coefficient as a measure of openness.

Results (More Fun!)

Here are the past 10 NCAA Men's Basketball Tournaments ranked by how even the field was going into the tournament:

Sure enough, this method indicates that this is the most even tournament field of the past decade (well, technically 11 years-- there was no tournament in 2020, so we went back an extra year to make it 10 tournaments).

An especially exciting corner of the bracket this year is the East Region, which features strong-but-not-invincible teams like Purdue, Marquette, and Kansas State. And when we look at the most open regions of the last 10 tournaments, the 2023 East Region tops the list:

For kicks, let's also check out the least balanced regions:

Perhaps not surprisingly, many of these regions featured juggernauts, including the 2021 Gonzaga (West Region) and 2015 Kentucky (Midwest) teams, leading to more imbalance in those parts of the bracket.

I wish I could use any of these numbers to help you with this year's bracket, but I'll leave the predictions to people who are smarter than me!

Happy March Madness!


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