Analyzing the results
a. What do the stem and leaf plots of the sample means and standard deviations indicate about the variation within each group and between the groups? Do both processes vary about the same? Are there differences in the patterns of variation?
b. Identify the different sources of variation. Which would you consider to be common cause variation and which special cause variation?
c. Compare the overall means and the boundaries for the two groups. Which of these two methods would you recommend and why?