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Variable Sampling Interval Combined Shewhart–Cumulative Score Quality Control Procedure
Author(s) -
Amin Raid W.,
Ncube Matoteng M.
Publication year - 1991
Publication title -
journal of the royal statistical society: series c (applied statistics)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.205
H-Index - 72
eISSN - 1467-9876
pISSN - 0035-9254
DOI - 10.2307/2347901
Subject(s) - statistics , interval (graph theory) , mathematics , sampling (signal processing) , confidence interval , computer science , filter (signal processing) , computer vision , combinatorics
SUMMARY A standard combined Shewhart–cumulative score quality control scheme for controlling the process mean takes samples from the process at fixed length sampling intervals. This paper proposes a modification which varies the time intervals between samples depending on what is being observed from the data. The properties of the proposed variable sampling interval combined Shewhart–cumulative score scheme are evaluated using a Markov chain approach. Results show that the scheme proposed is considerably more efficient than either the standard combined Shewhart–cumulative score chart or the standard cumulative sum chart.