Statistics play an important role in summarizing baseball performance and evaluating players in the sport.
Since the flow of a baseball game has natural breaks to it, and normally players act individually rather than performing in clusters, the sport lends itself to easy record-keeping and statistics. Statistics have been kept for professional baseball since the creation of the National League and American League, now part of Major League Baseball.
In baseball statistics, slugging percentage (abbreviated SLG) is a popular measure of the power of a hitter. It is calculated as total bases divided by at bats:
Gross Production Average or GPA is a baseball statistic created in 2003 by Aaron Gleeman, as a refinement of On-Base Plus Slugging (OPS). GPA attempts to solve two frequently cited problems with OPS. First, OPS gives equal weight to its two components, On Base Percentage (OBP) and Slugging Percentage (SLG). In fact, OBP contributes significantly more to scoring runs than SLG does. Sabermetricians have calculated that OBP is about 80% more valuable than SLG. A second problem with OPS is that it generates numbers on a scale unfamiliar to most baseball fans. For all the problems with a traditional stat like batting average (AVG), baseball fans immediately know that a player batting .365 is significantly better than average, while a player batting .167 is significantly below average. But many fans don't immediately know how good a player with a 1.013 OPS is.
The basic formula for GPA is: