A quality engineer at a canning company assesses whether the can-filling process is in control. Each hour, the engineer collects a subgroup of 10 cans. To minimize the within-subgroup (can-to-can) variation, the engineer collects the cans for a given subgroup in a short period of time.
The quality engineer creates a S chart to monitor the variation in the weight of the cans.
None of the points are outside the control limits, and the points display a random pattern. Thus, the process variation is in control, and the engineer can examine the process center on the Xbar chart.