There are numerous statistics used in baseball, including batting and pitching statistics. Batting statistics can be divided into several numbers. The batting average (AVG) is the number of hits a player makes divided by the number of times at bat. It does not include walks or sacrifice hits. The runs batted in (RBI) is the number of runners who scored on a player’s hit, base on balls, or sacrifice. The on-base plus sluggage (OPS) is a good measure of a hitter’s ability. This statistic combines getting on-base (on-base percentage, or OBP) and advancing runners (slugging percentage, or SLG). It is also more accurate thanks to the adjustment 1.2 × OBP + SLG, which compensates for the fact that SLG has a wider range than OBP.

Pitching statistics include the ERA and WHIP. The earned run average (ERA) is the earned runs times the innings in a game (most commonly nine) divided by the innings pitched. The walks plus hits per inning pitched (WHIP) records the bases on balls (walks) plus hits divided by innings pitched. It’s a good way to measure the approximate number of walks and hits a pitcher allows in each inning that he pitches. It then compares that amount to other pitchers to formulate a pitcher’s index.

The mathematical study of the American pastime of baseball is called “sabermetrics.”