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More on 13 vs. 14

Posted by Doug on November 21, 2006

Last week, following up on a comment from Bill M, Chase posted this fascinating data on how often teams win when they score a given number of points. The general pattern in the data is that teams that kick a lot of field goals tend to win more often than teams that score a similar number of points, but with more touchdowns. That sparked a number of interesting comments.

Many of those comments addressed the issue of correlation and causation. Just as rushing the ball 30 times is often an effect of --- rather than a cause of --- winning, so might be kicking field goals. On the other hand, there might be something "real" here. It might be that the ability to put together scoring drives is more important than the ability to score points. This would be related to various bits of conventional wisdom, such as that it's beneficial to control the clock and keep your defense off the field.

If the latter hypothesis is true, and if the ability to complete scoring drives is a persistent skill that teams have, then scoring 13 instead of 14 should signal success not just in the given game but also in future games.

To check this out, I looked at all teams that scored a given number of points and I checked their rest-of-season record. If 13 really is a better marker of team quality than 14 is, then teams that score 13 points instead of 14 in a given week ought to win more games not just in that week (that's what Chase showed) but for the rest of the season as well. To make sure I'm comparing apples to apples, I only looked at teams that were at home in the given week (so they'd have the same number of home and road games for the rest of the season).

Result:

Home teams that scored 13 points won 46.8% of the rest of their games (N=389).
Home teams that scored 14 points won 44.8% of the rest of their games (N=422).

Here is the full chart:


RestOfSeason
Score N WinPct
==========================
0 150 0.371
1 0 0.000
2 3 0.359
3 154 0.417
4 0 0.000
5 6 0.333
6 154 0.434
7 307 0.408
8 11 0.506
9 99 0.480
10 433 0.458
11 8 0.505
12 70 0.457
13 389 0.468
14 422 0.448
15 61 0.474
16 271 0.475
17 606 0.479
18 31 0.498
19 149 0.484
20 572 0.481
21 366 0.494
22 93 0.507
23 300 0.507
24 543 0.516
25 44 0.474
26 161 0.507
27 450 0.509
28 311 0.532
29 61 0.543
30 216 0.512
31 358 0.547
32 28 0.451
33 87 0.536
34 230 0.564
35 152 0.544
36 40 0.531
37 106 0.571
38 160 0.565
39 15 0.523
40 37 0.522
41 91 0.568
42 69 0.576
43 16 0.580
44 44 0.588
45 61 0.575

As you can see, the strange spikes are not as clear here. Thirteen is still "better" than 14, but 17 is better than 16, 21 is better than 20, 24 is better than 23, and 28 is better than 27.

Further, a breakdown of this table into winners and losers fails to point toward any kind of "ability to win by scoring 13 points instead of 14." Among just teams that won in the given week, teams that won with 14 points did better in the rest of the season than teams that won with 13. And this result held true basically straight down the line.


LOSERS WINNERS
Score N R-o-S W% N R-o-S W%
=============================================
0 152 0.373 0 0.000
1 0 0.000 0 0.000
2 3 0.359 0 0.000
3 150 0.415 4 0.506
4 0 0.000 0 0.000
5 5 0.347 1 0.267
6 137 0.427 15 0.508
7 291 0.399 14 0.554
8 11 0.506 0 0.000
9 73 0.452 26 0.558
10 347 0.441 77 0.533
11 6 0.417 2 0.769
12 46 0.412 24 0.542
13 252 0.453 134 0.499
14 319 0.430 101 0.507
15 28 0.415 34 0.523
16 117 0.454 153 0.493
17 332 0.460 269 0.500
18 12 0.467 19 0.515
19 57 0.446 92 0.509
20 208 0.439 360 0.504
21 168 0.443 198 0.537
22 34 0.484 59 0.517
23 67 0.465 230 0.522
24 176 0.462 369 0.542
25 18 0.459 26 0.484
26 28 0.422 134 0.525
27 92 0.408 358 0.536
28 77 0.425 233 0.566
29 8 0.411 53 0.563
30 14 0.468 202 0.516
31 58 0.488 299 0.558
32 3 0.200 25 0.480
33 10 0.502 77 0.541
34 26 0.565 203 0.565
35 16 0.533 135 0.546
36 4 0.367 36 0.545
37 6 0.464 100 0.578
38 9 0.406 151 0.575
39 3 0.533 12 0.520
40 2 0.359 35 0.532
41 4 0.531 87 0.570
42 1 0.400 68 0.577
43 0 0.000 16 0.573
44 0 0.000 44 0.588
45 0 0.000 61 0.577
46 0 0.000 4 0.574
47 0 0.000 11 0.592
48 0 0.000 27 0.566
49 0 0.000 14 0.532

[Table corrected at 10:30 a.m. central time]

This table is interesting both horizontally and vertically. Take a look at this chunk, for example:


LOSERS WINNERS
Score N R-o-S W% N R-o-S W%
=============================================
13 251 0.453 134 0.499
14 319 0.429 101 0.508

Losers who scored 13 did better than losers who scored 14, but winners who scored 14 did (very slightly) better than winners who scored 13. For each point value, the winners did better than the losers. The fact that the 14-point-scoring losers were the worst teams in the bunch lends some credence to the philosophy that a lot of those teams were probably overmatched, scored their second TD against a prevent defense, and lost by 10 or more.

The pattern is not exactly the same for the analagous slices of the table, like 16-17 or 20-21. But it is true that, in either column, the data is more smoothly increasing than it was in Chase's post. This says, I think (but I'm eager to hear comments), that the 13/14 disctinction is more about the particular game than it is about the team. Whether it's related to time of possession, number of scoring drives, or whatever, it's more effect than cause.

This entry was posted on Tuesday, November 21st, 2006 at 4:40 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.