Lies, Damn Lies, and Field Goal Percentage
(This is my small protest against the use of field goal percentage in newspaper boxscores everywhere. Another measure is needed.)
Believe it was Mark Twain who coined the phrase,"Lies, Damn Lies, and Statistics". After watching Jodie Meeks' fantastic shooting performance in the first half of the Pikeville exhibition, it brought back the memory of an old peeve.
We've had the three point basket for many years. Field goal percentage is still used to measure shooting performance or offensive efficiency although it is misleading,sometimes wildly misleading.
As an example, consider a hypothetical game(unlikely but possible)between,we'll call them,the Red Team and the Blue Team. In this game the Red Team had 60 field goal attempts making 30, all two point goals, for 50.0%. The Blue Team also had 60 attempts making 20, all three point goals, for 33.3%.
Current wisdom says the Red Team shot well(50.0%) while the Blue Team shot poorly(33.3%). How can this be ??? Both teams shot 60 times and achieved 60 points.
The problem is FG% is an unweighted average and treats all field goals the same,not taking into account that three is greater than two. What is needed is a weighted average to account for this.
Weighted Field Goal Percentage(WFG%)1.5 times three point goals +two point goals, all of that divided by field goal attempts(FGA). Take that result and multiply by 100%.
WFG%(1.5 X 3FG+ 2FG)/FGA then multiply the result by 100%
In the hypothetical game the Red Team had no three pointers, therefore WFG% is the same as FG%, or 50.0%.
The Blue Team made no two pointers so,
WFG%(1.5 X 20/60)X 100% 50.0%
We have an WFG% of 50.0% for both teams as it should be since both teams achieved the same nunber of points with the same number of shots.
Using WFG% Jodie Meeks' shooting is even more remarkable. In the first half he made 8 out of 10 FGA with 7 three pointers. His WFG% is,
WFG%(1.5 X 7+ 1)/10 multiplying the result by 100%=115.0%
Yes, WFG% may be more than 100%, and this shows the power of the three point basket. Meeks did something no two point shooter can do, he scored 23 points with 10 shots. A two point shooter making all ten shots could only score 20!!
Years ago Travis Ford had several games where he had a WFG% greater than 100%. He was a great offensive performer. In the NCAA tournament,his Senior year, UK was blowing teams out until they met Michigan in the Final Four. They shut him down and won in overtime.
A quick way to figure WFG% is to add half the number of 3 pointers made to total field goal attempts and then calculate like doing FG%. For Meeks first half shooting,
WFG%(3.5+ 8)/10 then multiply result by 100%
WFG%=115.0%
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8 comments
Comments
Interesting...
Good diary...
The Online home of Big Blue Nation ...
by JL Blue on Nov 3, 2007 10:28 PM EDT reply actions 0 recs
Thanks Blue
by 58Fan on Nov 8, 2007 1:26 AM EST up reply actions 0 recs
To me
by paralyzer on Nov 3, 2007 11:45 PM EDT reply actions 0 recs
Yes, but...
The Online home of Big Blue Nation ...
by JL Blue on Nov 4, 2007 12:11 AM EDT up reply actions 0 recs
True, but..
by paralyzer on Nov 4, 2007 1:06 AM EDT up reply actions 0 recs
I agree....
by MartinGolf9 on Nov 5, 2007 1:24 PM EST up reply actions 0 recs
I prefer the ...
That's what Ken Pomeroy uses, and I think it is a very good general predictor of how good a team is offensively.
It's counterpart, defensive efficiency, is the other side of that equation.
by Truzenzuzex on Nov 5, 2007 5:15 PM EST up reply actions 0 recs
Yes
Believe it's even better for football if you count a posession as any kick received (punts, kickoffs), then both offensive and defensive efficiency can be measured. If a team fumbles a punt or kickoff, or loses an onside kick, those would also count as a posession. Kicking teams would count as part of the defense, while receiving teams would count as part of the offense.
Rating a defense on points given up per game is misleading since high scoring teams give the ball back many more times. On average the more posessions a team has the more points they will score. Ball control teams often only appear to have better defenses since they give the ball back fewer times.
by 58Fan on Nov 8, 2007 1:22 AM EST reply actions 0 recs

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