The control chart is shown in Fig. 17.8. All samples are in control. If they were not, we would search for assignable causes of variation and revise the limits accordingly. Although this process exhibits statistical control, its capability (p 0.395) is very poor. We should take appropriate steps to investigate the process to determine why such a large number of defective units are being produced. Defective units should be analyzed to determine the specific types of defects present. Once the defect types are known, process changes should be investigated to determine their impact on defect levels. Designed experiments may be useful in this regard,