Discuss the difference between assignable cause variation and common cause variation. Discuss the difference between variables and attributes data. Discuss how it is possible for a process to be in control and yet produce a large percentage of nonconforming product. Discuss the difference between a Type I error and a Type II error. Under what circumstances might it be more appropriate to use 2 sigma control limits on a control chart rather than 3 sigma limits? Discuss what the term "out of control" means. How does a control chart signal that the process being monitored may be out of control? When is it preferable to use an attributes control chart instead of a variables control chart? What is the difference between the p-chart and the np-chart? What are the circumstances that require the use of Cpk rather than Cp as a measure of process capability? Under what circumstances would Cp and Cpk be the same? How does a delta chart differ from an x-bar chart? Under what conditions should a delta chart be used instead of an x-bar chart? When should an s-chart be used instead of a range chart? What is the appropriate control chart(s) to use to track the number of gallons of gasoline produced on a daily basis in a petroleum refinery? Does being in control always mean that a process is producing few defective items? What would be some possible explanations for a rising trend on an x-bar chart used to monitor moisture content in product emerging from a drying oven? How might shift-to-shift variation in the set-up of a process manifest itself in a control chart?