Acceptance sampling (ACCEPTSA)

Excel Spreadsheet Templates for Quality Control, Acceptance sampling. Sampling is the basis for most quality analysis. The ACCEPTSA model is used to sample incoming lots of material. The aim is to prevent lots containing unacceptable numbers of defective units from passing into the manufacturing system.

Acceptance sampling is a procedure for screening lots of incoming material. We decide whether to accept or reject the entire lot based on the results of a sample. A sampling plan is defined by two parameters: sample size and acceptance number. The acceptance number is the maximum number of allowable defects in the sample. If the sample contains this number or fewer defects, the lot is accepted without further inspection. If the sample contains more than the maximum number of defects, the lot is rejected and a 100% inspection is conducted.

The sample size and acceptance number determine the risks faced by the producer and consumer of the lot. The producer's risk is the probability that a "good" lot will be rejected by the sampling process. Lots are defined as good if they contain no more than a certain level of defectives called the acceptable quality level (AQL). The consumer's risk is the probability that a "bad" lot will be accepted. Lots are called bad if they contain more than a certain level of defectives called the lot tolerance percent defective (LTPD). Using the binomial distribution, the ACCEPTSA worksheet computes the producer's and consumer's risks, given the lot size, sample size, acceptance number, AQL, and LTPD.