What is "slugging percentage"

Slugging average \Slug"ging av`er*age\ (Baseball) a measure of the effectiveness of a batter at reaching base and advancing other runners, calculated as the sum of the number of bases reached on each hit, divided by the total number of times at bat. A double counts two bases, a triple three, a home run four. Thus a batter with four singles, two doubles and a triple in 20 official times at bat would have a slugging average of 0.550, and a batting average of 0.350. Also called slugging percentage. Compare batting average.

n. (context baseball English) A statistic which compares the total number of bases achieved by a batter over that batter's number of at bats.

In baseball statistics, slugging percentage (SLG) is a popular measure of the power of a hitter. It is calculated as total bases divided by at bats:

$\mathrm{SLG} = \frac{(\mathit{1B}) + (2 \times \mathit{2B}) + (3 \times \mathit{3B}) + (4 \times \mathit{HR})}{AB}$

where AB is the number of at-bats for a given player, and 1B, 2B, 3B, and HR are the number of singles, doubles, triples, and home runs, respectively. Walks are specifically excluded from this calculation. The name is a misnomer, as the statistic is not a percentage but a scale of measure whose computed value is a rational number in the interval [0, 4].

For example, in 1920, Babe Ruth played his first season for the New York Yankees. In 458 at bats, Ruth had 172 hits, comprising 73 singles, 36 doubles, 9 triples, and 54 home runs, which brings the total base count to . His total number of bases (388) divided by his total at-bats (458) is .847, his slugging percentage for the season, setting a record that stood until 2001, when Barry Bonds achieved 411 bases in 476 at-bats, bringing his slugging percentage to .863, unmatched since.