Page 185 - The Handbook for Quality Management a Complete Guide to Operational Excellence

172 P r o c e s s C o n t r o l Q u a n t i f y i n g P r o c e s s Va r i a t i o n 173

Sample 1 Range
110 None
103 7
97 6
96 1
105 9
110 5
100 10
93 7
90 3
103 13
97 6
103 6
90 13
97 7
99 2
106 7
90 16
96 6
109 13
90 19
91 1
108 17
96 12
101 5
96 5

Table 9.4 Data for Individuals and
Moving Ranges Control Charts

Since it is not possible to have a subgroup range less than zero, the
LCL is not shown on the control chart for ranges.

Control Limit Equations for Individuals Charts
sum of measurements
X =
number of measurements s
LCL = X E R = X − 2 66. × R
−
2
+
UCL = X E R = X + 2 66. × R
2
where E = 2.66 is the constant used when individual measurements are
2
plotted, and R is based on subgroups of n = 2.

09_Pyzdek_Ch09_p151-208.indd 172 11/21/12 1:42 AM