[ | Next | Previous | Up ]

Probabilty of defectives in a lot

From: Terry Bartlett
Date: 08 Jan 2003
Time: 13:14:07

Comments

How do I determine how many defective parts I can expect for a given confidence level, lot size and quality level? FOR EXAMPLE: A supplier manufactures cables at a quality level of 99.8% (or a defect rate of 2000 PPM). The customer receives a shipment of 300 cables. How does the customer determine which of the following is true: (a). He can be 95% confident that there will be no defective cables in the shipment. (b). He can be 95% confident that there is one or more defective cables in the shipment. And in the cases where there is likely one or more defective cables, how does the customer decide specifically how many to expect? In other words, can he determine a most-likely quantity of expected defectives at the 95% confidence level?


Last changed: November 20, 2007