One is faced with a decision to purchase parts from 3 suppliers. The part you need has a specification of 15.00 +/- 0.09 mm. The SPC studies done by suppliers indicate that their processes were in statistical control with the following process parameters.
Supplier A: X-double bar is 15.00 mm, ans Sigma-x is 0.03mm
Supplier B: X-double bar is 15.05 mm, ans Sigma-x is 0.022mm
Supplier C: X-double bar is 14.95 mm, ans Sigma-x is 0.015mm
Which Supplier would you select? Why?