5
Symbols and Notations
x
i
absolute value of x
i
C
p
a capability ratio
C
pk
a centered capability ratio
LSL
lower specification limit
n
the number of items in a subgroup
s
the standard deviation of a sample
s²
the variance of a sample
the standard deviation for a theoretical population of
measurements
the approximate standard deviation for a theoretical population of
measurements
2
the variance of a theoretical population of measurements
USL
upper specification limit
x
i
the summation of all x
i
’s
X
the average of a set of data
x
i
a single measurement
