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Ranking college football by the numbers

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My first attempt at a metric for ranking college football teams

John Rieger-USA TODAY Sports

Football has been slower than some other sports to adapt to today's numbers-driven world. Moneyball and Sabermetrics have slowly been taking over baseball, while tempo-free statistics and other data-driven methodology have changed the way basketball is played at the college and pro levels. While football hasn't completely ignored the wealth of data the game produces, the number of coaches refusing to punt on 4th and short, or insisting that defense wins games, hasn't dwindled as quickly as many of us would like.

As anyone who reads my posts here is likely aware, I'm a huge believer in analytics in sports. With college football being my favorite sport as a fan, I decided this year to combine  these passions and develop my own numbers-based ranking system for FBS level college football. I should note here that I'm hardly a trailblazing pioneer in this endeavor. Many others, perhaps most notably Bill Connelly, have been doing fantastic work at other sites, including over at SBN's own Football Study Hall, for years. In fact, I'll readily admit that what I've done here lacks some of the complexity you'll see in type of rankings published by sites like Football Outsiders.

Simply put, I don't have access to kind of data banks that larger sites are able to use. Everything you see in this article was painstakingly calculated by yours truly, using easily available basic statistics to develop something far more in depth that what you get by looking at rushing yards per game and completion percentage. I have devoted an embarrassing amount of time to this, but it is very much a beta version and a work in progress. Because I don't have access to the breadth of data available to some, I'm not able to do certain things, like eliminating garbage-time numbers, sorting efficiency numbers by down, or delving into field position data. Unfortunately, these are things that just aren't possible for me at this time, but again, I don't intend for this to be my finished product.

Methodology

My first steps in creating the formulas used here involved testing various statistics for their true value. I used the correlation coefficient to determine links between some common measures and overall team success. For those who slept through statistics, a correlation coefficient (or "r score" or "Pearson score") is a number between -1 and 1 that determines the strength of a relationship between two variables. For instance in 2013, yards gained per play and points scored per game had a CC of .8994, indicating a very strong positive relationship between the two numbers. In the other direction, points allowed per game and winning percentage had a CC of -.7933, meaning as points allowed increase, winning percentage is very likely to decrease (for obvious reasons).

I used numbers with a very high correlation to winning and scoring to develop my formulas. For my offensive rankings, a major factor is something I've referred to as "play efficiency," which is simply the percentage of plays that result in the most desired outcomes, either a first down or touchdown. The percentage of defensive plays where these outcomes are allowed factor heavily into the defensive ratings. Points scored/allowed and yards gained/allowed are also big factors.

For both offense and defense I generated a raw score based on these formulas, then adjusted for schedule using a combination of an RPI-style ranking, and the ratings for each opponent faced by each of the 126 teams. Yes, this means I sat in front of a computer and combed through the schedules of every single team in FBS to determine both the offensive and defensive strengths of schedule faced by each.

The overall ranking of a team encompasses these ratings, along with some other measures. For the KenPom crowd, "yard efficiency" and "scoring efficiency" are very similar to basketball's "efficiency margin." They are simply a team's yards gained per play minus yards allowed per play, or points scored per play minus points allowed per play.

I developed a formula using these two measures, my own offensive and defensive ratings, and few other smaller measures and adjusted for overall strength of schedule. The result is what I'm temporarily calling the Statistical Team Effectiveness Rating (super fun and creative, I know). The OSTER column indicates a team's offensive STE rating, and their offensive rank. Obviously, DSTER is the same for their defensive rating and ranking. I adjust each STE Rating such that the average rating is 100, just to provide a frame of reference when looking at the rating itself.

For right now, I'll give you my final 2013 rankings. I'll be using the same formulas to rate teams week by week moving forward, hopefully making adjustments as I go to improve the ratings. I will also make some predictive adjustments to last year's numbers and publish a set of preseason rankings later this week. Due to sample size issues, I will probably be basing the ratings for the first few weeks on the 2013 ratings, with increased weighting on 2014's early returns. So here it is, PenHawk's official 2013 college football rankings

Rank Team STE Rating OSTER Off Rank DSTER Def Rank Yard Eff Score Eff
1 Florida State 144.0708 142.7951575 1 137.4969322 1 3.58 0.5876
2 Alabama 131.6819 132.5774113 3 126.8155657 4 2.32 0.3661
3 Oregon 129.1992 134.5110967 2 122.3170625 3 2.94 0.3519
4 Baylor 127.9667 129.8354391 7 117.3815888 26 2.73 0.3233
5 Stanford 123.8387 119.2198457 15 121.6739226 2 1.49 0.2361
6 Missouri 123.7250 124.3861138 9 116.0604949 8 1.17 0.2265
7 Auburn 123.4229 130.2515699 4 106.7680867 20 0.96 0.1957
8 Ohio State 123.0385 129.8777729 6 110.3934803 38 1.87 0.3187
9 LSU 122.3547 128.2257951 8 111.5932312 31 1.86 0.2197
10 South Carolina 121.6842 122.4971742 12 114.2691869 15 0.93 0.1647
11 Clemson 120.1411 118.7517753 16 116.3732507 23 1.35 0.1897
12 Texas A&M 120.0090 130.0648279 5 93.36750534 60 0.98 0.1725
13 Wisconsin 119.7788 116.3194128 18 123.8353763 10 2.12 0.2441
14 Oklahoma State 119.1151 115.8070863 19 121.0094802 9 1.14 0.2470
15 Georgia 118.2600 123.0585799 10 101.6995011 37 1.25 0.0868
16 UCLA 118.0299 119.3380194 14 113.6655681 19 1.01 0.1964
17 Louisville 117.9875 112.8585759 27 130.0267583 22 2.5 0.3076
18 Michigan State 117.1159 107.4436403 35 133.251836 5 1.36 0.1997
19 Washington 116.6268 115.7825225 20 116.3886604 17 1.37 0.1899
20 Arizona State 116.3756 120.0902682 13 105.2509058 32 0.28 0.1092
21 Kansas State 115.6780 113.6744225 24 113.1643754 36 1.24 0.1978
22 USC 114.6282 113.2992065 26 114.3125471 16 1.07 0.1351
23 Miami (Florida) 113.3574 122.9346398 11 101.7036077 58 1 0.1752
24 UCF 112.8812 117.3008719 17 109.0088064 49 1.21 0.1993
25 Notre Dame 112.8289 110.6715253 28 112.452894 24 0.95 0.0942
26 Mississippi State 112.3713 107.3684253 37 109.9941192 14 0.46 0.0176
27 Oklahoma 112.2024 114.3739476 23 108.9897364 34 0.46 0.1137
28 Arizona 111.8486 107.6353477 34 113.4894766 25 0.53 0.1049
29 Georgia Tech 111.5182 114.6498321 21 105.322236 45 0.58 0.1487
30 North Carolina 111.2603 105.994319 42 112.898282 29 0.59 0.1299
31 Mississippi 110.6672 107.3919267 36 110.4146163 18 0.79 0.0471
32 Houston 109.6100 101.9504871 54 117.4287333 30 0.49 0.1782
33 Michigan 109.0899 108.2520058 32 105.4451871 35 0.15 0.0872
34 BYU 108.8726 103.512978 51 119.9676407 13 0.99 0.0734
35 Bowling Green 108.6478 105.8846799 43 117.540379 40 1.48 0.2453
36 Iowa 108.5563 98.94068884 66 121.9602771 7 0.68 0.0820
37 Utah 107.9828 105.5129788 45 106.6900479 28 0.13 0.0263
38 Cincinnati 107.9786 104.0375836 49 108.6537868 79 1.46 0.1063
39 Duke 106.8735 109.9156017 29 102.4917943 57 0.2 0.0913
40 Northern Illinois 106.4203 109.1472128 31 104.8296763 83 1.33 0.1873
41 Nebraska 106.0335 105.8634885 44 107.1921317 50 0.36 0.0829
42 Virginia Tech 106.0139 94.117201 80 120.4697907 6 0.47 0.0078
43 Utah State 105.8198 94.75404364 78 124.7581534 11 0.82 0.1802
44 Oregon State 105.3010 113.5702076 25 91.24225222 84 0.05 0.0194
45 East Carolina 105.1869 107.0999044 39 108.2641823 52 1.02 0.1785
46 Marshall 105.0270 101.0281297 57 111.822918 61 1.51 0.2353
47 Pittsburgh 104.7064 102.8487702 53 101.2549285 47 0 -0.0078
48 TCU 104.4211 93.51583368 83 114.9955718 21 0.2 0.0235
49 Boston College 104.1520 106.8080977 41 97.6469829 64 0.12 0.0559
50 Toledo 104.0925 103.4525434 52 96.62328403 77 0.55 0.0753
51 Vanderbilt 104.0866 107.2979298 38 105.3515826 51 0.34 0.0925
52 Texas Tech 104.0740 106.9668169 40 101.5331789 59 0.49 0.0191
53 Boise State 103.8143 99.71641424 61 109.0593643 53 0.76 0.1591
54 Texas 103.4550 100.0005288 60 107.4819795 33 -0.19 0.0319
55 Fresno State 102.8600 107.9418718 33 97.35012627 88 0.88 0.1209
56 Maryland 102.7276 100.308459 59 109.0673565 55 0.69 0.0383
57 Washington State 102.5973 104.1701458 47 96.85239738 56 -0.44 -0.0166
58 Navy 102.5576 103.5378461 50 101.5944303 63 0.16 0.1241
59 Indiana 102.5229 114.4510678 22 80.29426881 101 -0.16 0.0014
60 Penn State 102.1672 99.56761259 62 106.0781735 41 0.41 0.0141
61 Minnesota 102.0343 99.22736931 65 107.1231471 42 -0.43 0.0552
62 Florida 101.9058 91.72973827 88 111.3924657 12 -0.51 -0.0706
63 North Texas 101.6526 95.23295279 74 116.6209859 43 0.47 0.1727
64 Northwestern 101.6043 96.85897744 67 105.7157292 46 -0.07 0.0035
65 Ball State 101.1582 104.5485395 46 102.4837789 94 0.88 0.1897
66 Tennessee 100.6877 101.2320978 55 95.66142 48 -0.8 -0.0651
67 Syracuse 99.5969 96.08652148 73 106.0589145 44 -0.23 -0.0609
68 Louisiana-Lafayette 98.3852 104.1064398 48 95.22049607 100 0.39 0.1092
69 Tulane 98.0783 86.45775094 102 115.2819689 39 -0.25 0.0716
70 South Alabama 97.5300 94.78931129 77 101.7121204 71 0.17 0.0314
71 Western Kentucky 97.4769 99.23947885 64 100.0396414 87 0.96 0.0360
72 UTSA 96.8307 96.25807363 72 99.38613598 73 0.61 -0.0089
73 Arkansas 96.7778 96.32294534 71 90.2725766 65 -0.56 -0.1341
74 Arkansas State 96.5258 94.93460431 76 100.6577057 69 -0.18 0.0336
75 Illinois 96.3972 109.2360608 30 80.69818442 109 -0.75 -0.0789
76 San Jose State 96.3799 101.1127338 56 84.81314891 104 0.24 -0.0499
77 Florida Atlantic 95.8939 89.25444694 96 109.7162516 54 0.43 0.0376
78 Rice 95.2060 91.90835707 87 104.7171136 62 0.1 0.0398
79 Middle Tennessee 95.0920 94.94765997 75 104.908902 74 0.38 0.0607
80 Wake Forest 95.0686 83.69599171 106 112.9947408 27 -0.63 -0.0547
81 Colorado 95.0108 96.79245917 68 86.79744021 96 -0.74 -0.1308
82 Kentucky 94.5460 94.33526229 79 90.16624988 75 -0.97 -0.1393
83 West Virginia 94.4896 96.40633653 70 94.47453433 81 -0.39 -0.0792
84 Colorado State 94.4128 100.3463792 58 92.40849153 105 0.53 0.0702
85 San Diego State 93.5576 90.00813894 92 95.19726565 91 0.42 -0.0334
86 Memphis 93.1897 83.14135533 110 107.7411979 78 -0.51 -0.0516
87 Buffalo 93.1315 92.90061864 85 101.6008339 85 -0.27 0.0519
88 Rutgers 92.8068 93.20106671 84 95.43774188 82 -0.39 -0.0258
89 UNLV 91.7867 94.05236162 81 92.94631131 97 -0.34 -0.0285
90 North Carolina State 91.4995 87.9943252 97 93.3044132 72 -0.77 -0.1553
91 Ohio 91.0555 91.07216929 90 96.06679148 95 -0.19 0.0119
92 Iowa State 90.7296 91.27683954 89 89.60519932 92 -1.23 -0.1406
93 Temple 90.5502 89.97811822 93 92.60945695 98 -0.7 -0.0463
94 SMU 90.3331 93.957797 82 89.29183176 102 -0.05 -0.1108
95 Kent State 90.1530 87.4140346 99 94.64174342 90 -0.5 -0.0846
96 Akron 89.7487 83.24687846 108 98.64271994 67 -0.61 -0.1076
97 Louisiana-Monroe 89.1252 86.72711863 101 95.25149998 80 -0.79 -0.1014
98 Virginia 89.0755 83.62444295 107 94.87725159 66 -1.22 -0.2286
99 Troy 89.0057 99.39536439 63 77.41792696 114 -0.63 -0.0512
100 Texas State 87.9514 83.82726875 105 101.3816033 89 -0.33 0.0000
101 Connecticut 87.7036 83.1422826 109 95.57849898 86 -0.9 -0.1359
102 Hawai'i 86.8381 84.7022016 104 87.84525124 93 -0.7 -0.1210
103 Tulsa 86.6078 80.48852942 113 95.70212437 70 -0.85 -0.1586
104 Wyoming 86.3389 92.8358264 86 84.23108247 111 0.16 -0.0492
105 South Florida 85.7926 75.28681619 122 95.22910977 68 -1.12 -0.2109
106 Central Michigan 85.6753 87.07842114 100 91.01000568 108 -0.44 -0.0439
107 Nevada 85.5680 89.75228315 95 79.30919859 106 -1.83 -0.1529
108 Kansas 83.8610 77.7702784 118 94.33504 76 -1.53 -0.2053
109 Purdue 82.2019 80.04077635 114 80.64374503 99 -1.67 -0.2744
110 California 82.1596 90.4143897 91 65.87160757 115 -1.88 -0.3495
111 New Mexico 81.3446 96.65537859 69 56.83280415 121 -0.93 -0.1119
112 Louisiana Tech 80.8595 79.38327629 116 101.4299859 103 -0.18 -0.0731
113 Air Force 79.5739 85.42001143 103 72.03038367 116 -0.97 -0.1579
114 Army 78.5399 87.81022694 98 75.99262024 117 -1.06 -0.1577
115 Western Michigan 77.9472 76.75671973 119 83.36576342 107 -1.07 -0.2420
116 UAB 77.5103 89.97574715 94 56.58861877 122 -1.37 -0.2442
117 Georgia State 73.0429 78.71607349 117 83.53953373 110 -0.92 -0.2126
118 Idaho 72.5398 76.72184974 120 63.76667081 120 -2.12 -0.3765
119 Southern Mississippi 72.0775 75.83508453 121 71.64695781 118 -1.25 -0.3149
120 Massachusetts 71.8605 70.27910099 123 78.8036591 113 -2.31 -0.3246
121 New Mexico State 70.3944 82.29556907 111 57.25061763 123 -2.23 -0.3259
122 Eastern Michigan 67.7945 80.87043441 112 51.6764454 125 -2.45 -0.3844
123 UTEP 66.8687 80.03515272 115 55.3463258 124 -2.37 -0.3074
124 Miami (Ohio) 66.8655 64.16666337 124 81.15731425 112 -2.67 -0.3094
125 Florida International 64.2805 63.53084454 125 70.15116083 119 -2.96 -0.4078

I know how incredibly dry this is for many of you, so I appreciate you reading through this. Like I said at the beginning, this is very much a work in progress. I welcome any questions about my methodology, and definitely welcome any suggestions for improvement, so if anything jumps off the page and looks off, please let me know in the comments section and we can discuss it. You can also shoot me an e-mail with any questions or suggestions. Believe it or not, this stuff is a lot of fun for me, and I'd like nothing more than to eventually turn this into something bigger and much more useful

Questions? Comments? Please e-mail me at PenHawkRCT@gmail.com. You can also follow me on Twitter @kspen124