
262 A First Course in Quality Engineering
4.5 Summary on Control Charts
The discussion so for has been limited to the X- and R-, P-, and C-charts, and
some minor variations of these� These are the basic tools of process control
that are most useful in industry because of their applicability to many situa-
tions� Table 4�7 summarizes the information on these three basic types�
A few more sophisticated methods are available in the literature that are
useful under special circumstances� The cumulative sum chart is used when
higher sensitivity is needed to discover small changes� The exponentially
weighted moving average (EWMA) chart is also usefu ...