Assessing high-quality process performance using the quality-yield index: An innovative methodology

Manufacturers must meet high-quality standards and exceed customer expecta- tions to stay competitive due to significant technological advancements in recent decades. While implementing the yield measure is useful for achieving process performance by focusing on products that fall within specified limits, it does not accommodate specific customer requirements, particularly when a product’s quality characteristic deviates from target value. To address this need, the quality- yield index (Q-yield) has been proposed, which combines the process-yield index and loss-based capability index, providing a more advanced performance mea- sure. However, the Q-yield index’s confidence interval is challenging to derive due to the complicated sampling distribution involved. Several existing meth- ods have attempted to construct an approximate confidence interval but none have performed well. Therefore, this article proposes an innovative approach, called the generalized confidence intervals (GCIs), that utilizes the idea of gen- eralized pivotal quantities to establish the confidence interval for the Q-yield index. The proposed approach is evaluated through simulations and compared to existing methods. The results reveal that the proposed approach provides the most accurate results for constructing the lower confidence bound of the Q-yield index. This approach is recommended to evaluate process performance using the Q-yield index for high-quality customer requirements.