Newbie on basketball statistics

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josecarlos
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Re: Newbie on basketball statistics

Post by josecarlos » Mon Apr 09, 2018 11:22 am

Hi everybody!!!

I'm here again with my doubts!!! :) I'm making calculations about Offensive Rating and Defensive Rating aplying Dean Oliver's formulas. With Offensive Rating I haven't any doubt but with Defensive Rating ... I've got strange results in some cases. I'm applying the formula just only for a game right now, so ... ¿is it possible that I've got strange results because I'm making calulations for only one game? The strange result is that I've got a negative defensive rating with a player that only play two minutes. I have revised the formula several times, and all the intermedia calculations are right but the negative result occurs when I calculate the last step:

DRtg = Team_Defensive_Rating + 0.2 * (100 * D_Pts_per_ScPoss * (1 - Stop%) - Team_Defensive_Rating

So, what can I do in this cases? I mean, what is the more elegant solution to show in this cases? Show a negative value? Convert negative values to zero? Don't show anything?

And my second question about Offensive Rating and Defensive Rating is ... When I will make calculations to get the Offensive Rating or Defensive Rating about 5, 10, 20 games or all a regular season. What is better ... to sum all the Offensive Rating and Defensive Rating of each game and get the average or apply the formulas to all the games? I guess is the second option, but I would like to know how do you work in this cases if you previously have all the Offensive Rating and Defensive Rating previously calculated by game.

That's all!!! Thanks in advance for your appreciated help!!!

eminence
Posts: 56
Joined: Sun Sep 10, 2017 8:20 pm

Re: Newbie on basketball statistics

Post by eminence » Mon Apr 09, 2018 5:53 pm

Could you share the inputs for the player getting the negative result?

josecarlos
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Joined: Sun Oct 08, 2017 10:11 pm
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Re: Newbie on basketball statistics

Post by josecarlos » Tue Apr 10, 2018 9:55 am

eminence wrote:Could you share the inputs for the player getting the negative result?
Yes, of course!!! Here is the data ...

Code: Select all

Player
======
STL = 2
BLK = 2
DRB = 1
MP = 2
PF = 1

Team
=====
Team_DRB = 22
Team_BLK = 2
Team_MP = 200
Team_STL = 8
Team_PF = 19
Team_Possessions = 71

Opponent Team
==============
Opponent_ORB = 8
Opponent_FGM = 23
Opponent_FGA = 53
Opponent_TOV = 20
Opponent_FTA = 16
Opponent_FTM = 12
Opponent_PTS = 61

Intermedia calculations
=========================
DOR%: 0.26666666666666666
DFG%: 0.4339622641509434
FMwt: 0.6782841823056301
Stops1: 2.3217158176943697
Stops2: 0.2767818183528527
Stops: 2.5984976360472225
Stop%: 3.659855825418623
Team_Defensive_Rating: 85.91549295774648
D_Pts_per_ScPoss: 2.103448275862069

Final Result
===============
DRtg: -43.164988634172474

josecarlos
Posts: 63
Joined: Sun Oct 08, 2017 10:11 pm
Location: Spain
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Re: Newbie on basketball statistics

Post by josecarlos » Mon Apr 16, 2018 4:19 pm

josecarlos wrote:Hi everybody!!!

I'm here again with my doubts!!! :) I'm making calculations about Offensive Rating and Defensive Rating aplying Dean Oliver's formulas. With Offensive Rating I haven't any doubt but with Defensive Rating ... I've got strange results in some cases. I'm applying the formula just only for a game right now, so ... ¿is it possible that I've got strange results because I'm making calulations for only one game? The strange result is that I've got a negative defensive rating with a player that only play two minutes. I have revised the formula several times, and all the intermedia calculations are right but the negative result occurs when I calculate the last step:

DRtg = Team_Defensive_Rating + 0.2 * (100 * D_Pts_per_ScPoss * (1 - Stop%) - Team_Defensive_Rating

So, what can I do in this cases? I mean, what is the more elegant solution to show in this cases? Show a negative value? Convert negative values to zero? Don't show anything?

And my second question about Offensive Rating and Defensive Rating is ... When I will make calculations to get the Offensive Rating or Defensive Rating about 5, 10, 20 games or all a regular season. What is better ... to sum all the Offensive Rating and Defensive Rating of each game and get the average or apply the formulas to all the games? I guess is the second option, but I would like to know how do you work in this cases if you previously have all the Offensive Rating and Defensive Rating previously calculated by game.

That's all!!! Thanks in advance for your appreciated help!!!
Anyboby has any answer about my questions?

Crow
Posts: 5344
Joined: Thu Apr 14, 2011 11:10 pm

Re: Newbie on basketball statistics

Post by Crow » Mon Apr 16, 2018 4:52 pm

"is it possible that I've got strange results because I'm making calulations for only one game?"

Yes. And for only 2 minutes. 2 blocks and 2 steals in 2 minutes is just tremendous low sample size results and sorta breaks the normal scale. Accept that as a relative result and don't worry about it being negative.

"What is better ... to sum all the Offensive Rating and Defensive Rating of each game and get the average or apply the formulas to all the games?" I am not sure there is a certain "better" answer. Applying the formula to all games at once is most common but players actually play in and impact individual games. If it is easier for you, do the sum and average. In long run the difference will probably be small. The same method is applied to everyone. Might make slight difference between most consistent player and most inconsistent (consistent with themselves game to game or consistent with team within games) but I don't think many cases would be affected much. If you did it both ways you could find out and probably be the only one who knows.

Your questions show thoroughness, attention to detail. Asking questions is good but won't always work. Trust your own judgments. Lay out your methods and if someone offers a suggestion or opinion, listen to it & evaluate it. Go where you want with your analysis. Certainly don't let non-response to questions stop you for long. Do your best and listen. Asking twice shows persistence and persistence is good but even that won't always work. If you can't get an answer here, try reddit, real gm or use twitter to ask someone good at analysis. Not many post here anymore. Read here? Some still do, some don't.

josecarlos
Posts: 63
Joined: Sun Oct 08, 2017 10:11 pm
Location: Spain
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Re: Newbie on basketball statistics

Post by josecarlos » Tue Apr 17, 2018 9:50 am

Crow wrote:"is it possible that I've got strange results because I'm making calulations for only one game?"

Yes. And for only 2 minutes. 2 blocks and 2 steals in 2 minutes is just tremendous low sample size results and sorta breaks the normal scale. Accept that as a relative result and don't worry about it being negative.

"What is better ... to sum all the Offensive Rating and Defensive Rating of each game and get the average or apply the formulas to all the games?" I am not sure there is a certain "better" answer. Applying the formula to all games at once is most common but players actually play in and impact individual games. If it is easier for you, do the sum and average. In long run the difference will probably be small. The same method is applied to everyone. Might make slight difference between most consistent player and most inconsistent (consistent with themselves game to game or consistent with team within games) but I don't think many cases would be affected much. If you did it both ways you could find out and probably be the only one who knows.

Your questions show thoroughness, attention to detail. Asking questions is good but won't always work. Trust your own judgments. Lay out your methods and if someone offers a suggestion or opinion, listen to it & evaluate it. Go where you want with your analysis. Certainly don't let non-response to questions stop you for long. Do your best and listen. Asking twice shows persistence and persistence is good but even that won't always work. If you can't get an answer here, try reddit, real gm or use twitter to ask someone good at analysis. Not many post here anymore. Read here? Some still do, some don't.
Thank you so much Crow for your help again!!! You are very kind with me and my doubts!!! :)))

Do you have any suggestion about any thread in reddit?

Crow
Posts: 5344
Joined: Thu Apr 14, 2011 11:10 pm

Re: Newbie on basketball statistics

Post by Crow » Tue Apr 17, 2018 3:59 pm

I don't know much about reddit but you could start here and explore https://www.reddit.com/r/NBAanalytics/

At realGM this is the place https://forums.realgm.com/boards/viewforum.php?f=344

josecarlos
Posts: 63
Joined: Sun Oct 08, 2017 10:11 pm
Location: Spain
Contact:

Re: Newbie on basketball statistics

Post by josecarlos » Thu Apr 19, 2018 8:13 am

Crow wrote:I don't know much about reddit but you could start here and explore https://www.reddit.com/r/NBAanalytics/

At realGM this is the place https://forums.realgm.com/boards/viewforum.php?f=344
Thank you!!!

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