NCAA Tournament Bracket Formation: Which Factors Are Most Important to the Committee?

The purpose of this and some following posts is to provide information on which factors are most important to the Women's Soccer Committee in its at large selections and seeds for the NCAA Tournament.  The information isn't necessarily about which factors the Committee members individually think are the most important.  Rather, it's about which factors, when matched up with the Committee's decisions over the last 10 years, correlate best with the Committee's actual decisions and therefore are the most important, whether individual Committee members know it or not.

By "factors," I'm referring to 13 factors that the Committee is required by rule to use in deciding on at large selections for the NCAA Tournament.  The Committee isn't limited to those factors when it comes to seeding, but I'm satisfied that those factors are very important to seeding, too.  In addition, as I've covered in prior posts, I'm referring to each individual factor plus each factor combined in a pair with each other factor.

For each factor, whether individual or paired, I have identified patterns that match with the Committee's decisions.  A "yes" pattern means that over the last 10 years every team meeting that pattern has received a "yes" decision on a particular seed or at large selection.  A "no" pattern means that no team meeting the pattern has received a "yes" decision.

So, what I'll be covering here is which of the 13 individual factors' patterns and 78 paired factors' patterns match up the most frequently with the Committee's seeding and at large selection decisions.  The factors associated with these patterns are the most important factors, for seeding and at large selection purposes.

I'll start with the #1 seeds.  In the following post I'll cover the at large selections, and then I'll go through the #2, #3, and #4 seeds.

Here's a table for the #1 seeds, followed by an explanation:

Factor	Yes 1 Seed
ARPI Rating and Top 60 CO Rank	27
ARPI Rank and Top 60 CO Rank	27
CO Score and CO Rank	23
ARPI Rank and Top 60 CO Score	22
Conference ARPI and CO Rank	22
HTH Score and CO Rank	22
Top 60 CO Score	21
ANCRPI Rating and CO Rank	21
Conference Rank and CO Rank	21
Top 60 CO Rank	20
ARPI Rank and Conference Rank	20
CO Score and Last 8 Games (Poor Results)	20
CO Rank and Last 8 Games (Poor Results)	20
ARPI Rank and Conference ARPI	19
ARPI Rating and Conference ARPI	18
ARPI Rating and Top 60 CO	18
ARPI Rank and Top 50 Results Score	18
Conference ARPI and CO Score	18
ANCRPI Rank and CO Rank	17
Top 50 Results Score and CO Rank	17
Conference ARPI and HTH Score	17
HTH Score and CO Score	17
ARPI Rank and Rating	16
ARPI Rating and Conference Rank	16
ARPI Rank and Top 50 Results Rank	16
ARPI Rank and Top 60 HTH Score	16

This table shows the top 26 factors, whether individual or paired, in terms of which factors' patterns match the most often with the Committee's decisions.  Thus, for example, at the top of the table the pattern for the ARPI Rating/Top 60 Common Opponents Rank factor pair matches with actual #1 seeds 27 times over the last 10 years.  Or, to put it differently, if in 2006 I had had the factor patterns I now have, this particular paired factor pattern, by itself, would have "predicted" 27 of the 40 #1 seeds over the next 10 years.  The same is true for the pairing of ARPI Rank/Top 60 Common Opponents Rank.

The patterns for the factors that don't show up in the table would have "predicted" from 15 to 0 #1 seeds over the last 10 years.

What is significant to me about this table is how important teams' common opponent results are when it comes to #1 seeds.  As a reminder, and without going into a full explanation, the common opponent factor is something I developed to meet the NCAA requirement that the Committee consider results against common opponents.  For each top 60 team, I come up with a Common Opponent Score and Rank, based on how each team compares to each other top 60 team in results against opponents that the two teams had in common.

Also of interest, these top 26 factors in terms of #1 seeds include only two individual factors, with all the others being paired.  The two individual factors are the Top 60 Common Opponent Score and the Top 60 Common Opponent Rank, able by themselves to "predict" 21 and 20 of the #1 seeds, respectively, in other words half of the #1 seeds.

Looking over the balance of the list, it looks like teams' ARPI Ratings and ARPI Ranks are the next most important factors.

The "yes" patterns, however, are only part of the equation.  Although the "yes" patterns can identify a major portion of the #1 seeds, they can't identify all of them.  The "no" patterns also are important, since they exclude teams from #1 seeds.  This then leaves a few teams meeting no "yes" but also no "no" patterns, and these are the teams to choose from to fill any remaining #1 seed slots.

Here's a table showing the 25 factors that are most important in excluding teams from receiving #1 seeds:

Factor	No 1 Seed
ARPI Rank	527
ARPI Rating and Top 60 CO Rank	526
ARPI Rating and Top 60 CO	523
ARPI Rank and Last 8 Games (Poor Results)	522
ANCRPI Rank and CO Rank	522
ARPI Rank and Top 60 CO Rank	517
ARPI Rank and Rating	516
ANCRPI Rank and CO Score	516
ARPI Rank and Top 60 CO Score	515
ARPI Rating and Top 50 Results Rank	513
ARPI Rating and Conference ARPI	513
ARPI Rating and Last 8 Games (Poor Results)	513
ARPI Rating and Top 60 HTH	509
ARPI Rating	507
ARPI Rank and ANCRPI Rank	504
CO Score and Last 8 Games (Poor Results)	502
Top 50 Results Rank and CO Score	500
Top 60 CO Rank	497
HTH Score and Last 8 Games (Poor Results)	494
CO Score and CO Rank	493
ARPI Rank and Top 60 HTH Score	492
ANCRPI Rating and CO Score	491
Top 60 CO Score	489
ANCRPI Rank and HTH Score	487
ANCRPI Rating and CO Rank	486

To get these numbers in the right context, realistically speaking the pool of teams the Committee looks at in the at large selection and seeding process is the top 60 teams in the ARPI rankings.  So the above table is based on a pool of 600 teams over the last 10 years.  The "No 1 Seed" column then tells us how many of those 600 teams a particular factor's pattern has excluded from getting a #1 seed.

[NOTE:  The NCAA has a rule that no team with a record below 0.500 can receive an at large selection.  Over the last 10 years, 3 teams in the top 60 have had records below 0.500.]

This "No 1 Seed" table shows the most important factor patterns in excluding teams from getting #1 seeds are teams' ARPI Ranks and Ratings.  Indeed, each year the ARPI Rank factor pattern alone excludes 53 of the 60 possible teams from getting #1 seeds, limiting those seeds to coming from among the top 7 teams in the ARPI rankings.  Next in importance come teams' Common Opponent Scores and Ranks.