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Wednesday, March 14, 2018

NCAA Tournament 2018 Bracket Math for the MDS Model

Back by popular demand, bracket math is out for the MDS ModelAs I did last year, I've generated a composite set of rankings similar to what I used to sportsbet in Las Vegas. 

In the interest of time and specificity, I'm taking a composite of 4 different models, similar to what FiveThirtyEight does

  • FiveThirtyEight (so I'm including a composite of a composite)
  • KenPom (who's ratings are also included in FiveThirtyEight, so they're counted twice)
  • Powerrank (created and maintained by Ed Feng)
  • Massey Composite (another composite, this time spanning 68 rating systems)
Last year I also included Preseason poll rankings and Prediction Machine, a simulation engine. I've removed those this year partly due to time constraints, but also to make this composite entirely statistical model based (no simulation or human judgement). As I have in the past, I then use a weighted average of these 4 ratings that reduces outliers by weighting the ratings closer to the median higher. This smooths out the final Aggregate ratings that I then use to project the tournament.

Note: For simplicity, I've taken the highest rated team in each play-in game and included them.


SeedTeam1st Round2nd RoundSweet 16Elite 8Final FourChampionshipChampion
South
1Virginia100.00%97.54%75.91%55.83%37.00%24.66%14.61%
16UMBC100.00%2.46%0.28%0.03%0.00%0.00%0.00%
8Creighton100.00%55.18%14.08%6.67%2.64%1.04%0.34%
9Kansas St.100.00%44.82%9.73%4.12%1.43%0.50%0.14%
5Kentucky100.00%67.13%38.78%14.61%6.87%3.24%1.28%
12Davidson100.00%32.87%13.39%3.11%0.96%0.29%0.07%
4Arizona100.00%70.93%38.24%13.80%6.26%2.84%1.08%
13Buffalo100.00%29.07%9.59%1.83%0.47%0.12%0.02%
6Miami FL100.00%54.00%23.63%8.67%2.85%1.08%0.34%
11Loyola-Chicago100.00%46.00%18.44%6.11%1.81%0.62%0.17%
3Tennessee100.00%86.75%55.01%26.25%11.44%5.66%2.37%
14Wright State100.00%13.25%2.92%0.39%0.04%0.01%0.00%
7Nevada100.00%54.25%19.29%9.19%3.23%1.30%0.44%
10Texas100.00%45.75%14.62%6.36%2.00%0.73%0.22%
2Cincinnati100.00%88.87%63.25%42.37%22.89%13.79%7.25%
15Georgia State100.00%11.13%2.84%0.64%0.09%0.02%0.00%
West
1Xavier100.00%97.92%65.04%35.62%18.61%8.48%3.73%
16*Texas Southern100.00%2.08%0.11%0.00%0.00%0.00%0.00%
8Missouri100.00%43.74%13.85%4.90%1.61%0.44%0.11%
9Florida St.100.00%56.26%20.99%8.63%3.33%1.08%0.33%
5Ohio St.100.00%73.00%34.79%17.24%7.95%3.15%1.20%
12South Dakota St.100.00%27.00%7.08%1.92%0.47%0.09%0.02%
4Gonzaga100.00%79.35%51.16%29.77%16.30%7.82%3.64%
13UNC Greensboro100.00%20.65%6.97%1.93%0.48%0.10%0.02%
6Houston100.00%65.46%33.07%15.79%7.66%3.11%1.22%
11San Diego St.100.00%34.54%12.37%4.09%1.37%0.37%0.09%
3Michigan100.00%79.46%48.43%25.85%14.01%6.47%2.89%
14Montana100.00%20.54%6.12%1.47%0.36%0.07%0.01%
7Texas A&M100.00%60.36%22.75%10.03%4.21%1.45%0.48%
10Providence100.00%39.64%11.42%3.92%1.26%0.33%0.08%
2North Carolina100.00%93.03%64.65%38.71%22.39%11.15%5.38%
15Lipscomb100.00%6.97%1.18%0.14%0.01%0.00%0.00%
East
1Villanova100.00%97.06%77.51%54.71%36.79%23.51%14.79%
16*Radford100.00%2.94%0.43%0.04%0.00%0.00%0.00%
8Virginia Tech100.00%54.59%12.83%5.28%1.98%0.68%0.22%
9Alabama100.00%45.41%9.22%3.40%1.13%0.34%0.10%
5West Virginia100.00%73.76%42.85%17.35%8.82%4.17%1.93%
12Murray St.100.00%26.24%9.09%1.84%0.51%0.13%0.03%
4Wichita St.100.00%82.20%44.24%16.91%8.18%3.67%1.61%
13Marshall100.00%17.80%3.82%0.47%0.08%0.01%0.00%
6Florida100.00%67.09%34.39%14.97%5.62%2.33%0.94%
11*St. Bonaventure100.00%32.91%11.53%3.20%0.74%0.19%0.05%
3Texas Tech100.00%82.98%49.84%23.90%10.00%4.59%2.06%
14SF Austin100.00%17.02%4.24%0.70%0.09%0.01%0.00%
7Arkansas100.00%45.91%14.76%6.34%1.93%0.65%0.22%
10Butler100.00%54.09%19.30%9.06%3.07%1.16%0.42%
2Purdue100.00%94.56%65.21%41.75%21.05%11.53%6.19%
15CSU Fullterton100.00%5.44%0.73%0.08%0.01%0.00%0.00%
Midwest
1Kansas100.00%87.95%57.57%35.83%17.14%8.08%3.97%
16Penn100.00%12.05%2.65%0.54%0.06%0.01%0.00%
8Seton Hall100.00%56.50%23.91%11.87%4.23%1.47%0.54%
9NC State100.00%43.50%15.86%6.86%2.06%0.60%0.19%
5Clemson100.00%64.71%34.75%16.39%6.25%2.34%0.92%
12New Mexico St.100.00%35.29%13.97%4.63%1.17%0.29%0.08%
4Auburn100.00%80.48%46.28%22.89%9.24%3.66%1.52%
13Charleston100.00%19.52%5.00%1.00%0.14%0.02%0.00%
6TCU100.00%62.11%25.16%9.59%4.52%1.66%0.64%
11*Syracuse100.00%37.89%11.33%3.14%1.12%0.29%0.08%
3Michigan St.100.00%85.63%59.32%31.24%19.47%10.04%5.38%
14Bucknell100.00%14.37%4.19%0.74%0.17%0.03%0.00%
7Rhode Island100.00%51.74%13.99%5.08%2.02%0.61%0.19%
10Oklahoma100.00%48.26%12.41%4.31%1.65%0.47%0.14%
2Duke100.00%93.92%72.33%45.72%30.73%17.43%10.24%
15Iona100.00%6.08%1.28%0.16%0.02%0.00%0.00%

The top 8 teams in the tournament are as follows:


RankTeamRating
1Villanova93.98
2Virginia93.52
3Duke92.42
4Cincinnati91.10
5Purdue90.57
6Michigan St.90.54
7North Carolina89.54
8Kansas88.93
Villanova barely holds off Virginia for the top spot, and also barely has the highest probability of winning it all (14.79% vs Virginia at 14.61%). Definitely some differences between the committee's S-curve and the seedings: Virginia (#2 in my ratings) might face #4 Cincinnati in the Elite 8; Duke (#3) and Michigan St (#6) are a 2 and a 3-seed (respectively), and the 3rd 1-seed (Kansas) is #8 in my model.


A word of caution though about going straight chalk: in most pools you want to gauge "contrarian" picks relative to the overall pool. Most of the above picks are pretty chalky. A lot of people have found success taking my output and then changing the champion, for example. My cousin won my pool by taking Duke instead of Kentucky in 2015, I took Villanova successfully in 2016, and ironically enough, the only thing that stopped this model last year was that UNC beat Gonzaga in the final (had Gonzaga won, I would've won the pool with a Carolina loss in the final... again).

My suggestion is to do something like that - use the above probabilities as a guide, and make contrarian picks that have a good chance of happening (like taking a slightly different champion). #11 Loyola-Chicago over #6 Miami FL (46%) and most of the 8/9 and 7/10 matchups fit this criteria.

Here's the full rating set as well:


RankTeamRating
1Villanova93.96
2Virginia93.51
3Duke92.41
4Cincinnati91.09
5Purdue90.56
6Michigan St.90.53
7North Carolina89.53
8Kansas88.91
9Gonzaga88.88
10Michigan88.21
11Xavier87.98
12West Virginia87.87
13Texas Tech87.38
14Tennessee87.22
15Wichita St.86.99
16Kentucky86.38
17Houston86.17
18Auburn86.16
19Ohio St.85.77
20Arizona85.77
21Florida85.76
22Clemson85.33
23TCU85.06
24Seton Hall84.34
25Butler84.31
26Nevada83.97
27Texas A&M83.81
28Creighton83.61
29Miami FL83.07
30Florida St.83.00
31Virginia Tech83.00
32Arkansas82.88
33Texas82.48
34Rhode Island82.38
35NC State82.06
36Kansas St.81.79
37Oklahoma81.78
38Loyola-Chicago81.67
39Alabama81.39
40Missouri80.81
41Syracuse80.75
42San Diego St.80.62
43Davidson80.20
44Providence80.14
45New Mexico St.80.06
46St. Bonaventure79.59
47Murray St.79.00
48Buffalo78.08
49UNC Greensboro77.46
50South Dakota St.77.23
51Montana76.74
52Bucknell75.70
53Charleston74.18
54Marshall74.11
55SF Austin74.08
56Georgia State74.08
57Penn72.56
58Wright State71.67
59Iona70.82
60Lipscomb68.91
61CSU Fullterton68.19
62Radford67.61
63UMBC66.06
64Texas Southern59.56

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