Sigma Score (Z),

Definition of Sigma Score (Z):

1. A statistical measure that determines process capability. Sigma score produces an accurate analysis of observations or data, indicating the number of short-term standard deviations that fall above or below a specified mean. Also called sigma, sigma level or standard score.

   The formula to determine sigma score is: Z = X - M / D

   Where: X = raw score for standardization, M = population mean, and D = population deviation.