What is an upset?

Posted by nvr1983 on March 19th, 2008

I don’t know about you, but it always irritates me when people brag about calling a 9-8 upset. Although I guess it technically involves a lower seeded team beating a higher seeded team, we don’t consider it much of a surprise. I guess the nerd in us feels that the seeds are a little bit like a normal distribution/Bell curve. The middle seeds (7-10) are like the big peak in the middle of the curve and are separated by very little difference. However as you get further out on the distribution (like in the top 3 seed region) the difference between seeds becomes more noticeable. That’s why we would consider a 2 beating a 1 more of an upset than a 9 beating an 8 (assuming games are played on neutral courts). This doesn’t really come into play at the bottom of the distribution since the 15 playing the 16 seed is such a remote possibility that it isn’t even worth considering.

Here are some of the figures about the first-round matchups by seed since 1985 when we went to a 64-team tournament:
- #1 vs. #16: The #1 seed is 92-0 (100%).
- #2 vs. #15: The #2 seed is 88-4 (95.7%)
- #3 vs. #14: The #3 seed is 77-15 (83.7%)
- #4 vs. #13: The #4 seed is 74-18 (80.4%)
- #5 vs. #12: The #5 seed is 63-29 (68.5%)
- #6 vs. #11: The #6 seed is 63-29 (68.5%)
- #7 vs. #10: The #7 seed is 57-35 (62.0%)
- #8 vs. #9: The #8 seed is 42-50 (45.7%)

As you can see the #8 seed is actually under .500 in the first round. While it isn’t statistically significant, I think it is pretty clear that this game is really a toss-up.

On a related note, we found some of the Vegas lines interesting (taken from USAToday.com):
- #8 UNLV (+2) vs. #9 Kent State
- #8 BYU (+2) vs. #9 Texas A&M
- #7 Gonzaga (+2) vs. #10 Davidson

So Vegas actually favors one #10 seed and two #9 seeds.

We would like to hear what you consider an upset in the NCAA tournament. Do you consider a 9-8 an upset? A 10-7 an update? Or something else? Let us know.

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