Dean Oliver the four factors from sportingcharts.com

Sporting Charts explains The Four Factors

The first of the four factors is shooting. Effective Field Goal Percentage is used to determine team shooting efficiency. Turnovers are the next factor, and Turnover Percentage is the metric of choice for turnover efficiency.

Rebounding is the third factor, and Offensive Rebound Percentage is the analogous metric. Last of the four factors are free throws. Free Throw Rate tells us how effective a team is at getting to the foul line and converting those opportunities into points.

Dean Oliver, who is credited with creating this concept, has assigned weights to each of the four factors. He has determined that shooting is most important (40 percent), followed by turnovers (25 percent), rebounding (20 percent) and free throws (15 percent).

Each of the four factors can also be calculated for the defensive end of the floor

 essentially expanding the number of factors to eight. Interestingly, even though it is possible to create an overall team rating with The Four Factors, one rarely sees the data put together that way. The Four Factors are most often used to compare a team's strengths/weaknesses to another team's strengths/weaknesses in the four individual statistical categories.