It's your first day at the Jedi Temple, working as a lightsaber manufacturer. Your first task on the job is to analyze the control and capability of this process. Your main concern is to see if the lightsabers fit within the required length specifications set forth by the Jedi Council. The Jedi Council has provided you with 50 hours of data on newly crafted lightsabers. Each hour, 5 samples were measured.
A.) Create the appropriate set of X-bar control charts (use the Stat Menu). Are the mean and the variation both in control?
B.) In Control Chart options, enable all Tests. Are any of the Western Electric or Sensitizing Rules for control charts violated? Display the 2 sigma warning limits.
C.) If any out of control points correspond to assignable causes, omit them from the control limit calculation. What are the new control limits? Note that any out-of-control points should still be displayed on the control chart, with annotation to indicate why they were removed.
D.) A change to the process was made and 50 additional hours of data are reported. Create a control chart that shows both the old and new data in separate stages, with separate control limits calculated for each.
E.) Before assessing capability, it is important to determine whether your data follows a normal distribution. Using the Individual Distribution Identification tool, is this assumption reasonable? (Explain in terms of AD and P values).
F.) Is this system capable? Specification limits for lightsaber lengths are 2.75 and 3.25 ft. What do the Cp, Cpk, Pp and Ppk values indicate? Discuss in terms of the traditional benchmark value for a capable process, and indicate how well the process is centered between the specification limits. What sigma level is the process currently operating at, and what is the potential sigma level? What does this indicate about the variation WITHIN subgroups compared to the OVERALL variation?