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Calculating Individual Offensive and Defensive Ratings

Individual Offensive and Defensive Ratings are efficiency metrics developed by Dean Oliver in his 2004 book Basketball on Paper. What follows is a basic guide to their calculation, though we encourage you to read his book for the full details and explanation of these statistics.

Offensive Rating

In Dean's words, "Individual offensive rating is the number of points produced by a player per hundred total individual possessions. In other words, 'How many points is a player likely to generate when he tries?'"

The basic building blocks of the Offensive Rating calculation are Individual Total Possessions and Individual Points Produced. The formula for Total Possessions is broken down into four components: Scoring Possessions, Missed FG Possessions, Missed FT Possessions, and Turnovers.

The Scoring Possessions formula is by far the most complex:

where:

Missed FG and Missed FT Possessions are calculated as follows:

Total Possessions are then computed like so:

Now, Individual Points Produced must also be calculated:

where:

After all of that, we can finally calculate the player's individual Offensive Rating:

As a side note, we can also calculate what Oliver calls Floor Percentage, which answers the question, "What percentage of the time that a player wants to score does he actually score?":

The difference between Offensive Rating and Floor Percentage, Oliver notes, is the average number of Points Produced per Scoring Possession. "Though [Shaquille O'Neal] may have a high floor percentage," Oliver writes, "his poor foul shooting means that he has a lot of one-point possessions, bringing his offensive rating down a bit. Good three-point shooters like Reggie Miller, who may not have the highest floor percentage, will have higher offensive ratings."

Defensive Rating

Just as Oliver's Offensive Rating represents points produced by the player per 100 possessions consumed, his Defensive Rating estimates how many points the player allowed per 100 possessions he individually faced while on the court.

The core of the Defensive Rating calculation is the concept of the individual Defensive Stop. Stops take into account the instances of a player ending an opposing possession that are tracked in the boxscore (blocks, steals, and defensive rebounds), in addition to an estimate for the number of forced turnovers and forced misses by the player which aren't captured by steals and blocks.

The formula for Stops is:

where:

Also necessary is the calculation of Stop%, which is the rate at which a player forces a defensive stop as a percentage of individual possessions faced (essentially the inverse of Floor%, but for defenders):

With those numbers in hand, individual Defensive Rating can be computed:

where:

Notes: