Possession Calculations

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tsherkin
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Possession Calculations 

Post#1 » by tsherkin » Sun Sep 23, 2012 5:04 pm

So, I frequently see players being adjusted back to per-75-possessions instead of based on a per-minute rate as a way to create a pace-neutral environment in which to examine their numbers.

I'd love for someone to walk through the process of doing that. B-Ref doesn't track individual or team possessions in a sortable fashion, and posting formulae on the internet is always an awkward read because of all of the brackets involved. :( I've spent the last couple of hours trying to get my possession and pace data to match nbastatstuffer.com to no avail, and I'm sure it's because I'm making an error somewhere in the more specific possession formula that they use (instead of FGA + TOV - OREB + (.44*FTA).

Anyone? Bueller?
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Re: Possession Calculations 

Post#2 » by mysticbb » Sun Sep 23, 2012 8:06 pm

I'm not quite sure what your question really is, because basketball-reference actually has a column (sortable) to see the Pace of a specific team. Pace is the estimated amount of possessions per 48 min.

If you want to calculate the possessions for specific games, they have the formula described as well: http://www.basketball-reference.com/about/glossary.html

You can find that under Poss: Possessions (available since the 1973-74 season in the NBA); the formula for teams is 0.5 * ((Tm FGA + 0.4 * Tm FTA - 1.07 * (Tm ORB / (Tm ORB + Opp DRB)) * (Tm FGA - Tm FG) + Tm TOV) + (Opp FGA + 0.4 * Opp FTA - 1.07 * (Opp ORB / (Opp ORB + Tm DRB)) * (Opp FGA - Opp FG) + Opp TOV)). This formula estimates possessions based on both the team's statistics and their opponent's statistics, then averages them to provide a more stable estimate. The formula for players is rather lengthy and can be found in Dean Oliver's book.
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Re: Possession Calculations 

Post#3 » by tsherkin » Sun Sep 23, 2012 8:58 pm

mysticbb wrote:I'm not quite sure what your question really is, because basketball-reference actually has a column (sortable) to see the Pace of a specific team. Pace is the estimated amount of possessions per 48 min.


Pace I've seen, but I was talking about specific games, yeah. But ultimately, I was talking about taking a player's stats and converting them to per-75-possessions, and to see the process in action (even if it meant "insert possession calculation here" because obviously it'd be too unwieldy to place several times in a post).

0.5 * ((Tm FGA + 0.4 * Tm FTA - 1.07 * (Tm ORB / (Tm ORB + Opp DRB)) * (Tm FGA - Tm FG) + Tm TOV) + (Opp FGA + 0.4 * Opp FTA - 1.07 * (Opp ORB / (Opp ORB + Tm DRB)) * (Opp FGA - Opp FG) + Opp TOV)).


Ah, see this is what I was looking for. It parses better in pure text than where I was looking on NBAStatStuffer. Still need to dig out my copy of BOP, I've misplaced it but I'll find it soon enough.

Cheers!

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