Which of the Following Statements Are True?
A) It Is $\bar { X }$

Multiple Choice

Which of the following statements are true?

A) It is important to ensure that a process is under control with respect to location (equivalently, central tendency) as well as variation.
B) Most practitioners recommend that control of a process be established on variation prior to constructing an $\bar { X }$
Chart or any other chart for controlling location.
C) Charts for variation are based on the sample standard deviation S and also based on the sample range R.
D) Charts for variation that are based on the sample standard deviation S are generally preferred over charts that are based on the sample range R because the standard deviation gives a more efficient assessment of variation than does the range.
E) All of the above statements are true.