a. What are process data?

b. What does it mean for a process to be out of statistical control?

c. What are the three criteria for determining whether a process is out of statistical control?

d. What is the difference between random variation and assignable variation?

e. What is the difference between an R chart and an chart?

Monitoring Home Energy Consumption. In Exercises 2–4, use the following information: The author recorded his electrical energy consumption (in kilowatt-hours) for his home in upstate New York for two-month intervals over four years, and the results are listed in the table.