In the book Tools and Methods for the Improvement of Quality, Gitlow, Gitlow, Oppenheim, and Oppenheim present several control charts in a discussion and exercises dealing with pattern analysis. These control charts, which include appropriate A, B, and C zones, are reproduced in Figure 16.18. For each chart, identify any evidence of a lack of statistical control (that is, for each chart identify any evidence suggesting the existence of one or more assignable causes). In each case, if such evidence exists, clearly explain why the plot points indicate that the process is not in control.

Figure 16.18

a.

b.

Transcribed Image Text:

- UCL Zone A Zone B Zone C CNL Zone C Zone B Zone A LCL 10 20 30 Observation -UCL Zone A Zone B Zone C. CNL Zone C Zone B Zone A - LCL 1 5 10 15 Observation