power iso

In baseball, isolated power or ISO is a sabermetric computation used to measure a batter's raw power. One formula is slugging percentage minus batting average.




I
S
O
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S
L
G
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A
V
G


{\displaystyle ISO=SLG-AVG}





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T
B


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H


A
B





{\displaystyle ={\frac {{\mathit {TB}}-H}{AB}}}





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1
B


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2
B


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3
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H
R


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A
B



−


H

A
B





{\displaystyle ={\frac {({\mathit {1B}})+(2\times {\mathit {2B}})+(3\times {\mathit {3B}})+(4\times {\mathit {HR}})}{AB}}-{\frac {H}{AB}}}





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(


1
B


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+
(
2
×


2
B


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+
(
3
×


3
B


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+
(
4
×


H
R


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−
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1
B


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2
B


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3
B


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H
R


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A
B





{\displaystyle ={\frac {({\mathit {1B}})+(2\times {\mathit {2B}})+(3\times {\mathit {3B}})+(4\times {\mathit {HR}})-({\mathit {1B}}+{\mathit {2B}}+{\mathit {3B}}+{\mathit {HR}})}{AB}}}





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(


2
B


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+
(
2
×


3
B


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+
(
3
×


H
R


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A
B





{\displaystyle ={\frac {({\mathit {2B}})+(2\times {\mathit {3B}})+(3\times {\mathit {HR}})}{AB}}}

The final result measures how many extra bases a player averages per at bat. A player who hits only singles would thus have an ISO of 0. The maximum ISO is 3.000, and can only be attained by hitting a home run in every at-bat.
The term "isolated power" was coined by Bill James, but the concept dates back to Branch Rickey and his statistician Allan Roth.

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