Value Approximation Method
From SABR Encyclopedia
Value Approximation Method (VAM) is a baseball statistic invented by Bill James to compare players' seasons. VAM rewards both quality and quantity. VAM emphasizes its imprecise nature in both its name and by being an integer. A poor player who hardly played would have a VAM of 0, 1, or 2 while a league MVP usually is a little below 20. VAM was privately published by James in 1980[1] and first publicly published in 1982 [2].
[edit] Method For Pitchers
A) Each pitcher VAM is initially based on his season's games pitched:
0 for less than 30 G 1 for 30-54 2 for 55-79 3 for 80 or more
B) Add value for Innings Pitched:
0 for less than 40 IP 1 for 40-89 2 for 90-139 3 for 140-189 4 for 190-239 5 for 240-289 6 for 290-339
etc.
C) Add value for "net decisions" (2*Wins + 2*Saves - Losses)
0 for 0- 5 1 for 6-13 2 for 14-23 3 for 24-35 4 for 36-49 5 for 50-65 6 for 66-83 7 for 84 or more
D) Add 1 to VAM if he won 18 or more games
E) Add 1 to VAM if he led his league in ERA
F) Add 1 to VAM if he led his league in saves
G) Subtract rounded ERA adjustment from VAM but if this makes his VAM negative, his VAM is zero.
[edit] Method For Non-Pitchers
A) Each non-pitcher VAM is initially based on his season's games played:
0 for 0- 9 G 1 for 10- 49 2 for 50- 99 3 for 100-129 4 for 130 or more
B) Add value for Batting Average:
0 for .000-.249 1 for .250-.274 2 for .275-.299 3 for .300-.324 4 for .325-.349 5 for .350-.374 6 for .375-.399 7 for .400 or more
C) Add value for Slugging Percentage:
0 for .000-.299 plus 1 bonus if he has 70+ RBI 1 for .300-.399 plus 1 bonus if he has 70+ RBI 2 for .400-.499 plus 1 bonus if he has 100+ RBI 3 for .500-.599 plus 1 bonus if he has 130+ RBI 4 for .600-.699 5 for .700-.799 6 for .800 or more
D) Add value for Homerun Percentage:
0 for .000-.024 1 for .025-.049 2 for .050-.074 3 for .075-.099 4 for .100 or more 5 for .700-.799 6 for .800 or more
E) Add value for walks per AB:
0 for .000-.009 1 for .010-.019 2 for .020-.029 3 for .300 or more
F) Add value for stolen bases:
0 for 0-19 1 for 20-49 2 for 50-79 3 for 80 or more
G) Add 1 if his primary position is 2B, 3B, CF. Add 2 if it is SS.
H) If his primary position is 1B, add value for his defensive assists:
0 for 0- 99 1 for 100 or more
I) If his primary position is C, add value for his defensive games:
0 for 0- 9 1 for 10- 79 2 for 80-149 3 for 150 or more
J)If his fielding percentage is more than the league's average at the position, add 1.
K) If his primary position is 2B, 3B, SS, or any of the 3 OF positions AND his range factor is more than the league's average at the position, add 1.
L) If his primary position is 2B or SS, add value for his defensive double plays:
0 for 0- 89 1 for 90-119 2 for 120-149 3 for 150 or more
M) If his primary position is any of the 3 OF positions AND the sum of his assists and double plays exceeds 11, add 1.
N) If his primary position is C and his opposition stolen base rate (SBs/G) is smaller than league average, add 1.
O) If the player led his league in RBIs, add 1.
P) If the player had 200+ hits, add 1.
Q) The final step is to evaluate the non-pitcher's VAM in light of his part-time status. His part time status is the higher of the ratio of his ABs/500 or his (AB+W)/550. If either ratio is 1.0 or higher, there will be no change to the VAM. Otherwise his VAM is his calculated VAN times the part-time ratio. Round the VAM to the nearest integer.
