Situation For the past two years, Donna has assembled and tested electrical instruments that a customer will install in a vehicle. Because of customer complaints about instrument performance, Donna and her supervisor, Connie, carefully test 100% of the instruments and rework all of the ones that are out-of-specification. The electrical characteristics such as resistance are the most critical problem areas because instruments that are out-of-specification can cause the vehicle to malfunction. Recently, Connie questioned the measurement procedure itself. Donna assured Connie that she tests all instruments the same way each time. Both Donna and Connie recognize that there are problems to fix, but they are not certain where to start. Available data Donna keeps a record of all instruments tested and the results of the test on all characteristics. She has extracted some information from hand-written records pertaining to the number of instruments produced each week, the number that passed on the first test, the number that were reworked, the number that passed after rework and the number scrapped. Data for the past 15 weeks are shown in the table below entitled “Pass Fail Results for Instrument AFE 7983.” Questions 1. What are some ways that Donna might use these data to discover the root causes of the problems? 2. Analyze the data to determine if the production process is predictable with respect to percentage of instruments that pass the first test. 3. What other data does Donna need to collect to get to the bottom of the problem?
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