Widgets are made in a two-shift operation. Management is wondering if there is any difference in the proportion of defectives produced by these two shifts. They suspect that the second shift has a higher rate of defectives, since the workforce is not as highly trained and supervision may be lacking.
a. How would you use the p control chart to determine if there is a difference between the two shifts? Explain.
b. On the first shift, samples of size 200 have been used and p-bar = .06. Calculate CL, UCL, LCL for the first shift.
c. On the second shift, six samples of size 200 have been taken with the proportion of defectives .04, .06, .10, .02, .05, and .03. Using the samples from the second shift, has the process mean shifted upward or downward? Explain.