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Sports by the Numbers

Month: March 2017

Do Conference Championships Matter?

Posted on March 10, 2017March 10, 2017 by Peter Lemieux

All across the nation college basketball teams are participating in conference tournaments.  For the smaller programs, winning the conference tournament is nearly the only way to take part in the “Big Dance,” the NCAA Mens’ Tournament. Most of these conferences receive just a single bid to the tourney, one given to the winner of the conference’s tournament.  The mid-major and major conferences often send multiple teams to the Tournament.  The conference tournament winner receives one bid with one or more others selected “at-large” based on their performance over the course of the season.  Last year, for instance, two teams from the mid-major Missouri Valley Conference went to the Tournament – Northern Iowa, the tournament champion, and Wichita State which received an at-large bid.

“Bracketologists” have debated whether conference tournament victories matter in determining seedings, or whether the Tournament Committee ignores the conference tournament results in favor of each team’s “complete resume” including the regular season.  For instance, the Committee might give little weight to a conference tournament victory by a top team like Kansas which will already be getting a high seed.  Yet conference tournaments, even among the majors, are often not won by the top teams.

The average RPI for major conference champions since 2000 is just 0.63, only a bit better than the average of 0.61 for all major conference Tournament teams. While high RPI major teams get correspondingly high seedings in the Tournament, what about those more middling teams?  Does winning a conference championship improve their seedings in the Big Dance?

To study this, I have updated my models that predict seedings based on RPI and conference membership.  I have included the data for the 2016 Tournament, again excluding the “play-in” teams ranked 65th through 68th.  I use a team’s RPI, its conference membership, and “interaction” terms that allow the effects of RPI to different across the conferences.  To those predictors I add whether the team won a conference championship separated out by type of conference.

The basic results appear fairly similar to earlier models.  Both mid-major and major conference teams are rewarded with better seedings than the remaining teams from smaller conferences with identical RPIs.

The blue line represents teams in conferences that are considered neither mid-majors nor majors.  The line displays the predicted seedings for RPI values observed for these teams since 2000.  A couple of them have RPIs below 0.5, and aren’t represented in the graph, while the highest RPI any of these teams earned was 0.62, where the blue line ends in the graph.

The major and mid-major teams generally get much better seedings at identical RPI levels once we get above 0.56 or so.  Major conference teams also have an edge over the mid-majors that widens as RPI grows.  These results parallel ones I’ve reported on in earlier postings about seeding decisions.

If we add in so-called “dummy” variables for the champions, divided similarly among the three types of conferences, we get this rather startling result:

Winners of major conference championships have an average RPI score of 0.63, while mid-major winners average 0.58.  Without taking into account their championship victories, these teams are predicted to receive seedings of 3.5 and 10.1 respectively.  However if we add the estimated championship bonuses, those seedings improve to a top seed for major champions, and an eight or nine seed for mid-major champions.

Basketball pundits generally do not give much weight to conference championships, but the NCAA Tournament Committee apparently does.

 

Posted in NCAA Men's Basketball

Technical Appendix: The Model for Seedings with Champions Included

Posted on March 10, 2017March 10, 2017 by Peter Lemieux

This table presents the results of three “Tobit” estimations of the effects of RPI and conference membership on seedings in the NCAA Tournament.

The first column reports the results for a model that includes each teams RPI, its conference membership, and “interaction” terms for each combination of RPI and conference so that the slopes can differ across conferences.  RPI has a strong negative relationship with seeding, and that relationship is steeper for mid-major teams, and steeper still for majors.

The second column tests the hypothesis that the slope for majors and mid-majors are the same.  Here I include a variable that measures RPI for all major and mid-major teams together, then include a separate measure for the major conference teams.  If the majors and mid-majors followed the same path, the term for majors only in model (2) should be zero.  Since it is not, I maintain the distinction between majors and mid-majors in model (3).

This is the model where I add in whether a team won a conference championship. Champions from single-bid conferences actually have lower seeds because they are included in the Tournament automatically.  Since many of these are among the weaker teams, a tournament winner from a conference like the Colonial or Ivy receives a worse seeding than an average at-large team at the same RPI.

When we turn our attention to the mid-majors and majors, though, conference champions receive a substantial seeding bonus.  Mid-major champions have better (lower) seedings by a factor of 1.4.  For major champions the effect is a whopping 2.6 ranks.  Given the usual denigration of the conference championships by basketball pundits, these are surprisingly large effects indeed.

 

Posted in NCAA Men's Basketball, Technical Notes

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