Chair's message

In 1996, Pulak and Al-Sultan provided a rectifying sampling inspection plan for determining the optimal process mean. Assume that the quality characteristic is normally distributed with known process standard deviation and the larger-the-better characteristic (the conforming product with the lower specification limit). The 100% rectifying inspection is executed when the quality of the lot is rejected. Pulak and Al-Sultan (1996) obtained the optimal process mean under the maximum of the expected profit per item. Their model can be further applied in the output product control and process quality improvement for the production process. There is a major research objectives in this work: this study considers the effect of quality investment on the expected profit per item. From the above-mentioned purpose, we address the modified Pulak and Al-Sultan’s model which is different from the original model for comparing the effect on the expected profit per item. The numerical result show that the modified model has the larger expected profit per item than that of the original model. The result of this study reports that the policy of quality investment is available for enterprise’s practical application.