Scoring Index

From SABR Encyclopedia

Scoring Index is a baseball statistic invented by Earnshaw Cook to evaluate a hitter's or team's expected run production rate. Cook presented scoring index (he usually shortened it to DX) as one of the pillars of his book ^[1]. First edition was published in 1964 but a larger second edition was published in 1966 by M.I.T. Press. ^[2].

The concept of DX for a team is:

where

• A = Number of times team's players reached first base

• TB = Team's Total Bases
• PA = Team plate appearances

if DX < 0.100

if DX >= 0.100

[edit] "Stolen base" version of scoring index

Like Runs Created, Cook created a SB version of the formula:

where

• A = Number of times team's players reached first base
• TB = Team's Total Bases
• SB = Team's Stolen Bases
• PA = Team plate appearances

if DX < 0.1023

if DX >= 0.1023

[edit] Individual player scoring index

Cook's runs contributed for a player is the same concept as Runs Created, placing the player in an average environment. Runs contributed is the player's DX calculated as for the team is plugged into the R/PA formula and then multiplied by the number of player's PAs.

Cook suggests two possible modifications to the DX formula for an individual player. He suggests reducing A by the number of errors the player comitted in the field. He also suggested changing SB to SB less CS.

Cook also presented a method using the principle of DX to calculate a player's run statistic and his RBI statistic in the context of his team. For a player's RBI statistic, use the team's A rate (A of team/PA of team):

For a player's Run statistic, use the team's TB rate: