tag:blogger.com,1999:blog-5204092591876211047.post8463901875878662509..comments2023-03-23T07:34:12.473-04:00Comments on Advanced NFL Stats Community: Skinning the NFL catUnknownnoreply@blogger.comBlogger4125tag:blogger.com,1999:blog-5204092591876211047.post-62762143562954105072010-12-15T16:59:58.488-05:002010-12-15T16:59:58.488-05:00Bruce,
I think you're right. I was using team...Bruce,<br /><br />I think you're right. I was using team totals instead of combined totals which would make more sense.Brettnoreply@blogger.comtag:blogger.com,1999:blog-5204092591876211047.post-15806791713627852712010-12-13T17:28:57.883-05:002010-12-13T17:28:57.883-05:00Brett,
Thought a lot about your post.
Reran powe...Brett,<br /><br />Thought a lot about your post.<br /><br />Reran power without the MIN MAX limits, not much different at all.<br /><br /><br />So since power is the average of offense and defense, we can assume it reacts on points scored and given up, so maybe:<br /><br /><br />Using the GB ARI examples, first we can calculate against an average NFL team the following way. <br /><br /><br />GB offense at 1.169 is 16.9% better, so .169 * 22(avg points score)= +3.7 points(above avg) for GB, or 25.7 points(22+3.7)<br />and<br />GB defense at 1.169 is 16.9% better, so .169 * 22(avg points score)= -3.7 points(below avg) for AVG TEAM, or 18.3 points(22-3.7)<br /><br />So against an average team, GB should win by 6.4 points(25.7-18.3).<br /><br /><br /><br />ARI offense at .855 is 14.5% worse, so .145 * 22(avg points score)= -3.19 points(below avg) for ARI, or 18.81 points(22-3.19)<br />and<br />ARI defense at .855 is 14.5% worse, , so .145 * 22(avg points score)= +3.19 points(above avg) for AVG TEAM, or 25.19 points(22+3.19)<br /><br />So against an average team, ARI should lose by -6.89 points(25.19-18.81).<br /><br /><br />Now take the difference between +6.4 and -6.89, and GB should win over ARI by 13.29 points.<br /><br />Looks better.<br /><br />Or simply take the difference in power (1.169-.855)=.314, so GB is 31.4% better than ARI, on offense AND defense.<br /><br />So the total of the average points gained and average points given up in each game is 44(22+22)<br /><br />44 *.314(better %) = 13.8 points.<br /><br />That seems to fall in line with real world expectations.<br /><br />Thanks for the push to figure it out.<br /><br /><br />Also, home advantage this season seems to be about .02, not the .04 as stated above.Bruce D.http://i60200nfl.clanteam.comnoreply@blogger.comtag:blogger.com,1999:blog-5204092591876211047.post-39157107782130366282010-12-11T13:29:10.041-05:002010-12-11T13:29:10.041-05:00Brett,
I absolutely see(and have seen) your point...Brett,<br /><br />I absolutely see(and have seen) your point about looking too close to average.<br /><br />I had to "guestimate" the cut-off for MIN and MAX power per game.<br /><br />The MIN is .4, the MAX is 2(offense points above average and defense points below average per week/game). My reasoning is, no team can be more than 5 times better than another, even in one odd-ball game, and IMO there really is a fair amount of parity in the NFL.<br /><br />This kind of penalizes good teams that consistently blow out other teams, and boosts shut-out teams by not allowing a 0 offense rating.<br /><br />I'll change the cut-offs. and see if I can't get closer to realistic vegas odds. <br /><br />I'll post it here when done.Bruce D.http://i60200nfl.clanteam.comnoreply@blogger.comtag:blogger.com,1999:blog-5204092591876211047.post-89624711934707659182010-12-11T03:27:44.791-05:002010-12-11T03:27:44.791-05:00Great job, Bruce! I refer to your power rating met...Great job, Bruce! I refer to your power rating method as "subtractive synthesis" as opposed to Brian's method of "additive synthesis." Since the goal is to predict future outcomes and future outcomes are based on talent and luck (with luck being unknowable), then talent is what we are really trying to measure. Brian attempts to do this by adding together all the team stats that are caused by talent. Your method is just as valid if we assume TALENT = PAST OUTCOMES - LUCK and you are accurately measuring both PAST OUTCOMES and LUCK. The fact that your ratings are so close to Brian's shows that you have probably subtracted just the right amount of luck and Brian has added just the right amount of talent.<br /><br />My only criticism of your results is that your scale has all the teams rated too close to average. I believe the Packers are more than 17% above average, and the Cardinals are more than 15% below average. You can test this by converting your ratings to expected point values and comparing them to the Vegas lines. Since your average rating is 1.0, just multiply each team's rating by the average team score per game (22.25 points). Doing this gives the top-ranked Packers a point-rating of 26.01 and the bottom-ranked Cardinals a rating of 19.02, a difference of only 7 points. In reality, the Packers would probably be favored by 13-14 points on a neutral field. You can fix this by raising your ratings to the power of 1.8. This will adjust the scale to match the expected point-spread values. According to this adjusted scale, the Packers would have a rating of 1.32, and the Cardinals 0.75, which seems more accurate to me.Brettnoreply@blogger.com