APBRmetrics

I'm relatively new to APBRmetrics (actually, very new). I'm a small school college coach that stumbled upon APBRmetrics accidently, however, the more i have investigated, the more I am trying to figure out how to apply these principles to lower levels of basketball.

I'm also a history guy more than a math guy which means that conceptually ... I'm trying to overcome a lot to understand the math / theory behind the formulas.

I've read through Dean's book as a basic introduction and as the starting place as I try to apply these principles to my coaching. However... the one formula that I can figure our (either Dean doesn't explain it or I can't find in the book where he explains it) is "% Tm Poss".

Can anyone help me out and give me the formula he uses?

Also, I know his book was published in 2004. Are there any major changes to the use of his formulas since he published his work? I know a lot of the tweaking of formulas has to do with how you weight or value particular stats) but are there any conceptual ideas that since his work was published that he just got wrong.

Your thoughts are appreciated! Thanks!

Newbie

Welcome.

I don't remember exactly the formula he used, but I can tell you the general concept, and perhaps, you could make up a formula that is useful to you.

You know that a team takes N number of possessions per game. I don't know how many that is in college, maybe 50? 60? I really have no clue, but whatever that number is, that's your denominator.

The numerator can be calculated in different ways, but the way I would find useful would be:

P = FGM + DRB%*FGX + M*FTA + TOV

% TM POSS would then be 100 * P/N

In that formula:

P = total possessions "used" by player
FGM = field goals made by player
DRB% = team (or league) defensive rebound %
FGX = field goals missed by player
FTA = free throw attempts by player
TOV = turnovers by player
M = multiplier that converts FTA into possessions (in the NBA M ~ 0.44, not sure what it is in college)

Most of these terms should be fairly obvious. The one that may need a bit further explanation is the "DRB%*FGX". Basically, this accounts for the fact that not all missed shots result in the end of a possession, because the offense has a certain probability of getting the ball back with a rebound. For example, if you take 100 shots and miss 50 of them, you may get back 12 if the DRB% = 76% (just making up a number).

Other people have different ways of defining this. Like I said, you may want to use a formula that makes sense to you, but this is generally what it represents, i.e. the % of team possessions used by a player. I think most people refer to this now as "usage" (USG%).

I use .475 for converting college free throws to possessions. I got it off Wikipedia though so I'm not sure that's still the generally accepted value. http://en.wikipedia.org/wiki/APBRmetrics