Sequential Sampling Plan in the Truncated Life Test for Weibull Distribution

The truncated life test is usually applied for reducing experiment time. The lifetime of a product is assumed as its quality characteristic, and the sequential sampling (SS) plan is applied in the context of the truncated life test. In SS, the samples are selected from the lot stage by stage. In each stage, the total number of inspected items and the total number of defective items are specified, and then it is decided whether to continue sampling or to make a decision about the lot. A procedure is provided for computing the operation characteristic curve and average sample number (ASN) in the proposed SS plan. Moreover, a repetitive group sampling plan and a double sampling (DS) plan are also designed based on the truncated life test. Performance of the SS plan is compared with the DS plan and repetitive sampling plan. The application of these three sampling plans are illustrated in the industry using a real example. Finally, results of the comparison study indicate that the proposed SS plan has a better performance and could significantly reduce the ASN.