Rectifying LTPD Plans Minimizing Mean Inspection Cost Per Lot of Process Average Quality Using EWMA Statistics

摘要

The new lot tolerance percent defective (LTPD) variable sampling plans that minimize the mean inspection cost per lot of the process average quality, when the remainder of rejected lots is inspected, are introduced in this paper. The new plans are based on the usage of the exponentially weighted moving average (EWMA) statistic, and the economic advantages of the new plans over the existing plans with respect to the savings in the cost of the inspection are discussed. The methods for the calculation of the proposed plans have been implemented in a contributed package for the R computing environment, making the calculation of the parameters of the plans convenient for the cases where a particular situation in the business practice is not covered in the tables of the sampling plans.