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PLUS MINUS RATING: Definition & Applicability

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Author Topic: Plus Minus Rating: Definition / Applicability
horace_131

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Posts: 1

This topic is resumed: see below


Something about the Plus Minus Rating you refers to at the eBA Method section:

I understand this definition of rating: (on-court +/-) minus (off-court +/-)
These are all per-48 minutes measures. Don't you think it be better if the definition were the following?


Plus Minus Rating = (on-court +/-) minus (off-court +/-) plus (20% of average team +/-)

Alternatively, doing basketball analysis and not only stats-numbers, one could just normalize the Plus Minus Rating so that the average minutes-weighted rating for a given team was equal to the team's average plus/minus.
The Related Article: The basketball PLUS MINUS Rating by Daniel Ferrero
Lorenzo

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Posts: 4


I think we have to give the on-court and off-court numbers the same weight. If he did not do so, I am not sure how we would interpret the plus / minus rating.
Making the measure a per 100 possessions measure it's better rather than per 48 minutes: that's means, it's a very good thing anytime we are able to remove the effect of pace.

d_ferrer

eBA Stats Team
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Posts: 24


 This statistical method measure how point differentials change when a particular player is in game versus when he is not, evaluating how the team is performing in both situations.


+ / - Rating = On court Points - Off court Points

On Court Points= Team's net points ( Pts scored by team - Pts scored by opponent )
                         with the particular player on the floor.

Off Court Points= Team's net points ( Pts scored by team - Pts scored by opponent )
                         with the particular player off the floor.
 


Analyzing Plus / Minus Data

* Logic of this method is straightforward: teams should perform better when their good players are playing versus when they are not.

* The pure "unadjusted" plus / minus rating do not measure the value of the player per se; they measure the value of the player relative to the players that substitute in for him.

* There are differences in the quality of players that players play with and against.

* A weak starter on a team with exceptionally good starters ( relative to bench players ) will generally get a very good unadjusted plus / minus rating - regardless of his actual contribution to the team.

* Star players play a lot of minutes per game and will generally have a plus / minus rating that mirror the team's number as a whole.

* When the team gets beaten by a solid margin, the team as a whole will probably have very few players with a positive rating.

* A situation when a player have a NEGATIVE rating ON court and a POSITIVE while on bench, MUST NOT be lightly analyzed as this player should have been played MORE minutes.

* Players on poor teams have a hard time getting good plus numbers, due to the fact that their teams are usually behind.

* We must use the plus / minus statistical formula as just ANOTHER of many tools available at eBA basketball Statistics Creative Analysis System that will help the coach to evaluate the team, not as a exclusive one.

* A good aspect of tracking plus/minus rating is that the players will be aware that the coach is grading the team's performance for every second a particular player is on the floor.

* Also gives role players or player's who aren't necessarily big scorers or into compiling big personal statistics, another way to evaluate and feel good about what he is doing on the court.

( From my article: basketball Plus Minus Rating at eBA Stats.com )

 Smiley  Daniel Ferrero -  ebastats - the basketball statistics forum

 
trezeguet

eBA Stats Team
Jr. Member
*****
Posts: 18

This post RESUMES the topic.

The eBA basketball Statistics Creative Analysis System tries to compare team success to individual performance, applying reasonably simple methods.
 
If we want to apply the Plus / Minus Ratings to suggest how a certain sequence of players would perform on the floor against an average opponent, we must determine the sum of each of the five players. We must perform the total sum of all of them and no average them. So the team's average plus / minus needs an adjustment be added, which is explained at the eBA System.
 
We must take into account, using the Plus / Minus Ratings that the overall debate about this rate has dismissed the effect of opponent strength because + / - rate doesn't measure player combinations for the opponents. On the other hand, there is no way to recognize between players who have good individual but bad team numbers, opposed to players with bad individual statistics but good + / - ratings.
 
The suggestion about giving on-court and off-court numbers different weights doesn't resolve this rates problems, because it would give us a rate too contingent on the overall grade of excellence worth of the player's team and in most cases this will have a very minor effect.

So, the real method for efficient results is to refrain from applying the Plus / Minus Ratings exclusively,  without any other method being involved, as a possession based method, for example.
 
As said, resuming, the Plus / Minus rating determines the dimension of the statistical norm difference in team accomplishment when a player is on the court opposed to when he is not. We must concede the validity of the difference in quality of the players that a given player plays with and against, when he is on and off the court. Only when they are the same, or almost the same, the Plus / Minus Ratings will determine the dimension of that given player effect on team's winning percentage compared to that team's average. 

 Smiley  Jean Louis Trezeguet -  ebastats - the basketball statistics forum

This post resumes this topic and will be completed at the "Statistics" chapter of the eBA basketball Statistics Analysis System.  Another basketball statistics topics you'll find at the basketball Statistics Discussions section of our eBA Stats.com site.

 

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