# Four Factors

How do basketball teams win games? While searching for an answer to that
question, Dean Oliver
identified what he called the "Four Factors of Basketball Success":

- Shooting (40%)
- Turnovers (25%)
- Rebounding (20%)
- Free Throws (15%)

The number in parentheses is the approximate weight Mr. Oliver assigned
each factor. Shooting is the most important factor, followed by
turnovers, rebounding, and free throws. [Editor's note: I agree with the order, but disagree
with the weightings.] These factors can be applied to both a
team's offense and defense, which in a sense gives us eight factors.
Let's take a closer look at how these factors are measured, using the 2004-05 Phoenix Suns as an example.

### Shooting

The shooting factor is measured using Effective Field Goal Percentage
(eFG%). The formula for both offense and defense is (FG + 0.5 * 3P) /
FGA. For the Suns offense this is (3351 + 0.5 * 796) / 7018 = .534, and
for the defense it is (3328 + 0.5 * 494) / 7485 = .478.

### Turnovers

The turnover factor is measured using Turnover Percentage (TOV%). The
formula for both offense and defense is TOV / (FGA + 0.44 * FTA + TOV). On
offense, the Suns turnover percentage was 1125 / (7018 + 0.44 * 2080 +
1125) = .124, while on defense it was 1131 / (7485 + 0.44 * 1775 + 1131) =
.120.

### Rebounding

The rebounding factor is measured using Offensive and Defensive Rebound Percentage (ORB%
and DRB%, respectively). The formula for offense is ORB / (ORB + Opp
DRB), while the formula for defense is DRB / (Opp ORB + DRB). In 2004-05,
the Suns offensive rebound percentage was 967 / (967 + 2550) = .275, and
their defensive rebound percentage was 2652 / (1233 + 2652) = .683.

### Free Throws

The free throw factor is a measure of both how often a team gets to the
line and how often they make them. The formula for both offense and
defense is FT / FGA. The Suns free throw rate on offense was 1556 / 7018
= .222, and on defense it was 1320 / 7485 = .176.