Chapter 12 Quality Control 507
Figure 12-13
The Steel
workbook
or 1, a very large subgroup size might be required for the approximation to
be legitimate.
The lower and upper control limits are
LCL 5 p 23
Å
p^112 p^2
n
UCL 5 p 13
Å
p 112 p 2
n
P Chart Example: Steel Rod Defects
A manufacturer of steel rods regularly tests whether the rods will withstand
50% more pressure than the company claims them to be capable of with-
standing. A rod that fails this test is defective. Twenty samples of 200 rods
each were obtained over a period of time, and the number and fraction of
defects were recorded in the Steel workbook.
To open the Steel workbook:
1 Open the Steel workbook from the Chapter12 data folder.
2 Save your workbook as Steel Control Chart. See Figure 12-13.
