charts for process monitoring
1.Take samples of size n from the process at regular
intervals. Plot the means of
these samples against the
order in which the samples were taken.
2.We know that the sampling distribution of under the process-monitoring conditions is Normal with a mean m and a standard deviation
. Draw a solid center line
on the chart at height m.
3.The 99.7 part of the 68-95-99.7 rule for Normal
distributions says that as
long as the process remains in control, 99.7% of the values of will fall within three standard deviations of the
mean. Draw dashed control limits on the chart at these heights. The control limits mark off the range of variation in sample means that we
expect when the process
remains in control.
4.Process monitor.
