Title
A Novel Approach To Deriving The Lower Confidence Limit Of Indices C-Pu, C-Pl, And C-Pk In Assessing Process Capability
Abstract
Process capability indices (PCIs) are widely used as a measure of process potential and process performance. Unfortunately, the use of sample data to estimate PCIs means that any error in the sampling can introduce considerable uncertainty into the assessment of process capability. This necessitates the use of the lower confidence limit (LCL) in the estimation of minimum process capability. Furthermore, the complexity of sampling distributions of the PCIs greatly hinders interval estimation, such that only an approximate or asymptotic LCL can be achieved. This paper proposes a novel approach to deriving the 100(1 - alpha)% LCL of indices C-pu, C-pl and C-pk using Boole's inequality and DeMorgan's theorem. This approach is based on subsample data collected from a stable process. Hypothesis testing is also used to determine whether the process is capable of satisfying the quality requirements of customers. We calculated the critical values of the PCIs for various significance levels, capability requirements and sample sizes. Finally, we present analysis of two cases to demonstrate the applicability of the proposed approach.
Year
DOI
Venue
2017
10.1080/00207543.2017.1282644
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
Keywords
DocType
Volume
process capability indices, lower confidence limit, process performance, Boole's inequality, DeMorgan's theorem
Journal
55
Issue
ISSN
Citations 
17
0020-7543
4
PageRank 
References 
Authors
0.48
5
3
Name
Order
Citations
PageRank
K.S. Chen1409.35
Kung-jeng Wang219220.36
Tsang-Chuan Chang3142.91