The McGranger Mortgage Company of Problem 6 made some changes to the process and undertook a process capability study. The following data were obtained for 15 samples of size 5. On the basis of individual observations, management estimated the process standard deviation to be 4.21 (days) for use in the process capability analysis. The lower and upper specification limits (in days) for the mortgage process times were 5 and 25.

a. Calculate the process capability index and the process capability ratio values.
b. Suppose management would be happy with three sigma performance. What conclusions is management likely to draw from the capability analysis? Can valid conclusions about the process be drawn from the analysis?
c. What remedial actions, if any, do you suggest that management take?

Transcribed Image Text:

Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Mean 11 12 8 16 13 12 17 16 13 14 17 9 15 14 9 Range 9 13 4 11 10 9 8 15 14 11 6 6 12 10 11