SAMPLING INSPECTION SCHEMES WITH SWITCHING RULES FOR LIFE TESTS BASED ON EXPONENTIAL DISTRIBUTION

A life test is a random experiment which is performed on manufactured items such as electric and electronic components in order to estimate their lifetime by selecting the items randomly from the production process. The lifetime / lifespan of the product is a random variable that follows a specific continuous-type probability distribution, called the lifetime distribution. Reliability sampling, which is one among the classifications of product control techniques, deals with inspection procedures for sentencing one or more lots or batches of items submitted for inspection. An acceptance sampling scheme is a combination of sampling inspection plans with switching rules for changing from one plan to another. A switching rule is an instruction within a sampling scheme for changing from one sampling plan to another of greater or lesser severity of sampling based on the demonstrated quality history. In this paper, the concept of sampling schemes for life tests with a switching rule involving two samples under the assumption that the lifetime random variable follows an exponential distribution is introduced. A procedure is developed for designing the optimum sampling schemes with minimum sample sizes when two points on the desired operating characteristic curve are prescribed providing protection to the producer and the consumer.