Advances and Applications in Statistics
Volume 2, Issue 2, Pages 119 - 130
(August 2002)
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PROCESS INCAPABILITY INDEX FOR CONTAMINATED NORMAL PROCESSES
G. H. Lin (Taiwan)
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Abstract: Greenwich
and Jahr-Schaffrath [Inter. J. Quality & Reliability
Management 12(4) (1995), 58-71] introduced the
process incapability index Cpp
= Cip
+ Cia, which
provides an uncontaminated separation between
information concerning the process precision and
process accuracy. Pearn and Lin [Quality &
Reliability Engg. Inter. 17 (2001), 279-290]
investigated the statistical behavior of the natural
estimators of the three indices, Cip,
Cia,
and Cpp
for normal processes. In this paper, we consider the
natural estimators of the three indices for
contaminated normal processes, a class of processes
often seen in real applications. We derive the r-th
moments and obtain some distributional and
inferential properties of the estimators of the
three indices. We also develop tests for the three
indices based on their natural estimators.
Practitioners can use the tests to determine if
their processes meet the preset capability
requirement. |
Keywords and phrases: process incapability index, contaminated normal process, inaccuracy index, imprecision index. |
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