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kjb
Joined: 03 Jan 2005
Posts: 860
Location: Washington, DC
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 Posted: Mon Oct 10, 2005 8:51 am Post subject: |
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| Ed Küpfer wrote: | | I've set up a new four-factors based set of historical stats pages. Nothing too comprensive, but hopefully somethings that you can't find anywhere else. I'm kinda proud of the HTML-based graphs and sparklines. |
I like it. Might want to double-check the formulas, though. You have the Wizards with a pts per 100 possession last season of 112.4 scored, and 112.8 allowed -- they were in the 107 range for both last season. |
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Ed Küpfer
Joined: 30 Dec 2004
Posts: 783
Location: Toronto
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| Posted: Mon Oct 10, 2005 10:17 am Post subject: |
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| WizardsKev wrote: | | Might want to double-check the formulas, though. You have the Wizards with a pts per 100 possession last season of 112.4 scored, and 112.8 allowed -- they were in the 107 range for both last season. |
The discussion from this thread suggests that we are overestimating (edit, wrote underestimating before) the number of possessions by using the traditional FGA + .44*FTA - OR + TO formula. I used FGM + .4*FTM + OppDR + TO, which gave me a good fit to Roland's pbp possession counts. I don't think it's very important in the context of the website—what matters is the relative differences between offense and defense.
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Last edited by Ed Küpfer on Mon Oct 10, 2005 10:57 am; edited 1 time in total |
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kjb
Joined: 03 Jan 2005
Posts: 860
Location: Washington, DC
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| Posted: Mon Oct 10, 2005 10:27 am Post subject: |
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| Ed Küpfer wrote: | | WizardsKev wrote: | | Might want to double-check the formulas, though. You have the Wizards with a pts per 100 possession last season of 112.4 scored, and 112.8 allowed -- they were in the 107 range for both last season. |
The discussion from this thread suggests that we are underestimating the number of possessions by using the traditional FGA + .44*FTA - OR + TO formula. I used FGM + .4*FTM + OppDR + TO, which gave me a good fit to Roland's pbp possession counts. I don't think it's very important in the context of the website—what matters is the relative differences between offense and defense. |
I'd thought Justin's numbers were updated to the newer possessions estimator. Justin? |
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jkubatko
Joined: 05 Jan 2005
Posts: 702
Location: Columbus, OH
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| Posted: Mon Oct 10, 2005 12:12 pm Post subject: |
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| WizardsKev wrote: | | I'd thought Justin's numbers were updated to the newer possessions estimator. Justin? |
I'm using Dean Oliver's estimator:
| Code: | | FGA + 0.4*FTA - 1.07*(ORB / (ORB + Opp DRB))*(FGA - FG) + TO |
| Ed Küpfer wrote: | | I used FGM + .4*FTM + OppDR + TO, which gave me a good fit to Roland's pbp possession counts. |
For the three years of data I have from 82games, the rmse of the formula above is 2.48 possessions per game. The rmse of Oliver's formula using the same data is 1.49 possessions per game. Ed, if you want to use a formula like the one above, you should probably increase the free throw multiplier to something like 0.52.
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Justin Kubatko
Basketball-Reference.com |
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Ed Küpfer
Joined: 30 Dec 2004
Posts: 783
Location: Toronto
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| Posted: Mon Oct 10, 2005 4:34 pm Post subject: |
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| jkubatko wrote: | | Ed, if you want to use a formula like the one above, you should probably increase the free throw multiplier to something like 0.52. |
I can't in good concience use a coefficient greater than 0.5. It would violate my code of ethics, as well as the Universal Declaration of Free Throw Rights. I will, however, multiply my possession estimates by 0.96, which should bring everything back to the neighbourhood of orthodox estimates.
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jkubatko
Joined: 05 Jan 2005
Posts: 702
Location: Columbus, OH
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| Posted: Mon Oct 10, 2005 4:49 pm Post subject: |
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| Ed Küpfer wrote: | | I can't in good concience use a coefficient greater than 0.5. It would violate my code of ethics, as well as the Universal Declaration of Free Throw Rights. I will, however, multiply my possession estimates by 0.96, which should bring everything back to the neighbourhood of orthodox estimates. |
It also changes all of your coefficients, including the free throw coefficient. :-)
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Justin Kubatko
Basketball-Reference.com |
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kjb
Joined: 03 Jan 2005
Posts: 860
Location: Washington, DC
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| Posted: Tue Oct 11, 2005 4:50 am Post subject: |
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| The formulation I liked from the previous thread -- simple and easy to calculate -- was .96 * FGA + .44 * FTA - ORB + TOV. |
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jkubatko
Joined: 05 Jan 2005
Posts: 702
Location: Columbus, OH
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| Posted: Tue Oct 11, 2005 7:55 am Post subject: |
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| WizardsKev wrote: | | The formulation I liked from the previous thread -- simple and easy to calculate -- was .96 * FGA + .44 * FTA - ORB + TOV. |
Be careful. That should be:
| Code: | | 0.96*(FGA + 0.44*FTA - ORB + TOV) |
I'm sure that's what you meant, but the way you typed it it looks like the 0.96 multiplier only goes with FGA.
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Justin Kubatko
Basketball-Reference.com |
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kjb
Joined: 03 Jan 2005
Posts: 860
Location: Washington, DC
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| Posted: Tue Oct 11, 2005 8:19 am Post subject: |
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| jkubatko wrote: | | WizardsKev wrote: | | The formulation I liked from the previous thread -- simple and easy to calculate -- was .96 * FGA + .44 * FTA - ORB + TOV. |
Be careful. That should be:
| Code: | | 0.96*(FGA + 0.44*FTA - ORB + TOV) |
I'm sure that's what you meant, but the way you typed it it looks like the 0.96 multiplier only goes with FGA. |
I was being forced to pay retail for the parentheses.  |
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Analyze This
Joined: 17 May 2005
Posts: 364
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| Posted: Wed Oct 12, 2005 8:06 am Post subject: |
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| Ed Küpfer wrote: | | WizardsKev wrote: | | Might want to double-check the formulas, though. You have the Wizards with a pts per 100 possession last season of 112.4 scored, and 112.8 allowed -- they were in the 107 range for both last season. |
The discussion from this thread suggests that we are overestimating (edit, wrote underestimating before) the number of possessions by using the traditional FGA + .44*FTA - OR + TO formula. I used FGM + .4*FTM + OppDR + TO, which gave me a good fit to Roland's pbp possession counts. I don't think it's very important in the context of the website—what matters is the relative differences between offense and defense. |
Very nice. Ik hope you will update every season. 
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Ed Küpfer
Joined: 30 Dec 2004
Posts: 783
Location: Toronto
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| Posted: Wed Oct 12, 2005 11:01 am Post subject: |
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| The Big Dipper wrote: | | Very nice. Ik hope you will update every season. |
Actually, I'm kinda hoping someone will steal the idea and do it for me, updating during the season. I did this a few years ago, but I changed ISPs and my new one won't let me publish directly from Excel. I'm not very good with html and web stuff, so I won't be able to figure out a good way of doing it, but maybe someone else wants to do the work. Anyone interested can email or PM me and get technical advice on the stats themselves.
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