List of Symbols – Six Sigma for Business Excellence: Approach, Tools and Applications

List of Symbols


α Producer's risk
β Consumer's risk (Also see the row below)
β Shape parameter for Weibull distribution
χ2 Value of chi-square distribution
Cp Capability index
Cpk Capability index considering process centering
Average difference between two samples
η Median
Ho Null hypothesis
H1 Alternate hypothesis
k Letter used for number of bins, or number of factors
κ Cohen's kappa
μ Population mean
n Number of data points or sample size
N No of total observations
p Probability of an event
Pp Process performance index
Ppk Process performance index considering process centering
q (1-p) i.e., Probability that the event does not occur
r Correlation coefficient
Sample standard deviation
σ Population standard deviation
Se Standard deviation of errors
σp Standard deviation of process output
σt Standard deviation of observed variation
σm Standard deviation of measurement system
Sp Pooled standard deviation
σ2 Variance
Sx Sample standard deviation of x
Standard deviation of sample means
Sxy Sample covariance
Sy Sample standard deviation of y
θ Scale parameter for Weibull distribution
X Key process input variable
x or xi Individual values of data
Sample mean
Grand mean
Y Key process output variable
Z Value of standard normal transformation