Situation In an attempt to assure that incoming parts from various vendors meet all requirements, one manufacturing firm requires evidence of conformance to specifications. In particular, all vendors must perform a final audit of packaged product. The results of this audit, expressed in defective units per million, are included with all shipments. All units that are found to be defective are sent to rework to determine the cause of the defect. Available data One vendor ships all of its product to the manufacturer. A final audit of packaged product is performed daily on 10% of the units packaged that day. The data for 4 weeks are summarized below. The date, number of units inspected, number of units rejected, and the defects per million (DPM) are included. Questions 1. How can these data assure the manufacturer that all product will meet specifications? 2. How can these data be used by the vendor and the manufacturer to determine what can be expected in the future? 3. What are the problems in expressing results in defects per million when only one to two thousand units are inspected? 4. What would be a better way for the vendor to supply data to reassure the manufacturer of conformance to requirements?
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