Title: An improved approach for constructing lower confidence bound on process yield

Authors: Chien-Wei Wu; Mou-Yuan Liao; James C. Chen

Addresses: Department of Industrial Management, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan. ' Department of Finance, Yuanpei University, No. 306, Yuanpei St., Hsinchu 30015, Taiwan. ' Department of Industrial Management, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan

Abstract: Process yield, the percentage of processed product units passing inspection, is a standard numerical measure of process performance in manufacturing industry. Based on the expression of process yield, Boyles (1994) presented a yield-measure index, S_pk, for normally distributed processes. In order to compute the index value, sample data must be collected and a great degree of uncertainty may be introduced into the yield assessment due to sampling errors. To remedy for this, several existing techniques have been applied to construct the confidence bounds for S_pk. In this article, an alternative approach is proposed to construct the lower confidence bound for S_pk. To examine and compare the performances of the proposed generalised confidence intervals (GCIs), a series of simulations is conducted. The results show that the proposed GCIs approach is superior to the standard bootstrap in terms of coverage rate. Therefore, this article recommends GCIs approach for assessing the process yield in real applications. [Received 4 November 2010; Revised 5 January 2011; Accepted 7 January 2011]

Keywords: bootstrap; generalised confidence intervals; GCI; lower confidence bound; process yield; performance measurement; manufacturing industry; simulation.

DOI: 10.1504/EJIE.2012.046667

European Journal of Industrial Engineering, 2012 Vol.6 No.3, pp.369 - 390

Published online: 10 Sep 2014 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article