Saturday, December 17, 2016

Guess the Lines Week 16

Here are the week 15 results and week 16 predictions for this installment of "Guess the Lines". This is a weekly feature in which I put my Vegas NFL rankings to the test by predicting the point spread of upcoming NFL games. I compare the accuracy of my prediction against those of Bill Simmons and Cousin Sal, as featured on their weekly NFL podcast. In addition, I also calculate an implied point spread from ESPN Chalk's weekly Vegas NFL rankings.

Here are the week 15 results. Cousin Sal wins this week with a mean absolute prediction error of 0.94 points.

Week 15 Resultspredicted point spread:
gameaGPFhGPFmeespnbillsalactual
CLE @ BUF -8.3 0.8 -11.5 -11.5 -8.0 -13.0 -10.0
TB @ DAL -0.2 5.6 -8.5 -7.0 -4.5 -7.5 -7.0
IND @ MIN -0.6 0.9 -4.0 -4.5 -4.0 -3.5 -3.5
MIA @ NYJ -1.8 -5.8 +1.5 +1.0 +3.5 +2.5 +3.0
PHI @ BAL 0.1 2.0 -4.5 -4.0 -6.5 -6.0 -6.5
SF @ ATL -7.7 3.6 -14.0 -15.0 -9.0 -13.0 -13.0
JAC @ HOU -4.8 -3.5 -4.0 -7.5 -7.0 -8.5 -6.0
DET @ NYG -0.1 0.4 -3.0 -2.5 -3.5 -3.0 -4.0
GB @ CHI 0.9 -5.5 +4.0 +5.5 +7.5 +6.5 +6.5
CAR @ WAS -0.5 1.8 -5.0 -4.0 -3.0 -6.0 -4.5
NE @ DEN 6.7 2.4 +2.0 0.0 +3.5 +4.5 +3.0
OAK @ SD 2.5 0.7 -0.5 +0.5 +3.0 +4.5 +3.0
LA @ SEA -5.0 5.7 -13.0 -13.0 -13.0 -14.0 -14.0
NO @ ARZ 0.3 0.6 -3.0 -5.0 -3.0 -4.0 -2.5
PIT @ CIN 5.3 0.8 +2.0 +0.5 +2.5 +3.0 +3.5
TEN @ KC 0.0 2.9 -5.5 -5.5 -7.0 -6.0 -5.5
Mean Absolute Error 1.34 1.59 1.13 0.94

The closest prediction for each game is shown in bold. As a reminder, my predictions and the ESPN predictions were made a week ago Tuesday, so as not to be influenced by the week 15 opening lines.

Here is a summary of the weekly results. A lower score is better (we are measuring average prediction error). My rankings have now dropped to third, behind both Bill and Sal. The ESPN Chalk rankings are a distant fourth.

Mean Absolute Prediction Error:
week me espn bill sal
10 1.29 1.86 1.89 1.68
11 1.11 1.46 1.29 1.07
12 1.38 1.75 1.28 1.22
13 1.13 1.70 0.87 1.10
14 1.53 1.91 1.00 1.66
15 1.34 1.59 1.13 0.94
average 1.30 1.71 1.24 1.28

Inspired by a suggestion in the comments in the week 12 post, I have also summarized how well each participant predicted the actual margin of the game:

Mean Absolute Prediction Error (actual margin):
week me espn bill sal vegas
10 9.32 9.61 8.79 8.64 9.54
11 5.25 5.25 4.14 3.93 4.57
12 8.44 8.69 8.16 7.59 7.50
13 12.43 12.33 13.10 12.73 12.77
14 8.56 7.56 7.47 6.75 7.59
average 8.80 8.69 8.33 7.93 8.39

Over four weeks, both Bill and Cousin Sal have done a better job than Vegas at predicting actual results. For reference, over the long term the average miss in the Vegas line is about 10 points. My rankings have actually fared the worst so far in predicting actual margins.

Week 16 Predictions

Here are the week 16 predictions for both my model (based on the Tuesday version of my Vegas rankings), as well as the December 13 rankings from ESPN Chalk.

Week 16 Predictionspoint spread
gameaGPFhGPFmeespnbillsalactual
CIN @ HOU 1.0 -2.3 +1.0 -2.0
DEN @ KC 2.0 3.1 -3.5 -2.5
TB @ NO -0.1 0.4 -3.0 -1.0
ARZ @ SEA 0.8 4.5 -6.0 -5.0
SD @ CLE -0.7 -8.2 +5.0 +6.0
IND @ OAK -0.8 3.2 -6.5 -4.5
MIA @ BUF -2.1 -0.1 -4.5 -4.5
ATL @ CAR 3.8 0.0 +1.5 +3.0
SF @ LA -7.7 -6.6 -3.5 -4.5
NYG @ PHI 0.8 -0.3 -1.5 -1.5
NYJ @ NE -6.2 6.9 -15.5 -14.5
DET @ DAL -0.5 5.0 -8.0 -7.5
BAL @ PIT 2.4 5.9 -6.0 -6.0
WAS @ CHI 2.2 -5.3 +5.0 +3.5
TEN @ JAC 0.2 -5.2 +3.0 +2.0
MIN @ GB 1.0 3.0 -4.5 -3.5

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