If dimensional data are sampled from three machines that execute the same milling operation on parts in a machining process, what type of control chart(s) would you use for this operation? Would you apply data from all three machines on the same control chart or would you use separate control charts for each machine? What factors would you consider in determining rational subgroup size? Note: See Example 6.11 in Introduction to Statistical Quality Control 8th edition by Douglas C. Montgomery.