Estimated Runs Produced

Estimated Runs Produced (ERP) is a kind of run estimator, similar to linear weights, created by Paul Johnson. It was originally published in Bill James's 1985 Baseball Abstract.

The original formula was:

(2 x (TB + BB + HP) + H + SB - (.605 x (AB + CS + GIDP - H))) x .16 = Runs

Johnson also has a version of the formula to use when Caught Stealing is not available:

(2 x (TB + BB) + H + SB - (.615 x (AB - H))) x .16 = Runs

And a slightly more accurate version of the above:

(2 x ( TB + BB) + H + SB - ( .610 x (AB + (SB/4) - H))) x .16 = Runs

Ironically James lauds ERP as being more accurate than Linear Weights, when actually ERP is a linear weights formula. Unlike Batting Runs, ERP is baselined against (near) absolute zero, while BR is baselined against the league average.

Johnson later updated his formula, introducing "New" Estimated Runs Produced in the 1991 Baseball Scoreboard:

(TB*.318) + ((BB - IBB + HP - CS - GIDP)*.333) + (H*.25) + (SB*.2) - (AB*.085)