Question: Lengths of steel shafts are measured by a laser gauge that produces a coded voltage proportional to shaft length (above some reference length). In the units produced by the gauge, shafts of a particular type have length specifications 2300 ± 20. Below are measured lengths of n = 10 such shafts. Assume the shafts came from a physically stable process.
(a) Using a normal distribution model for shaft length, give 90 % confidence limits for a process capability index that measures process potential.
(b) Using a normal distribution model for shaft length, give 90 % confidence limits for a process capability index that measures current process performance.
(c) Based on your answers to (a) and (b) what do you conclude about the current and potential process performance?