Production yield measure for multiple characteristics processes based on STpk under multiple samples

Process yield is an important criterion used in the manufacturing industry for measuring process performance. Methods for measuring yield for processes with single characteristic have been investigated extensively. However, methods for measuring yield for processes with multiple characteristics have been comparatively neglected. Chen et al. (2003) proposed a measurement formula called S^Tpk , which provides an exact measure of the overall process yield, for processes with multiple characteristics. In this paper, we considered the natural estimator of S^Tpk under multiple samples, and derived the asymptotic distribution for the estimator. In addition, a comparison between the SB (standard bootstrap) and the proposed method based on the lower confidence bound is executed. Generally, the result indicates that the proposed approach is more reliable than the standard bootstrap method.