Open AccessEconomic-statistical design of synthetic np chart with estimated process parameter
Author(s) -
Ming Ha Lee,
Michael B. C. Khoo,
XinYing Chew,
Patrick Then
Publication year - 2020
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0230994
Subject(s) - chart , process (computing) , statistics , function (biology) , estimation theory , computer science , \bar x and r chart , control chart , statistical process control , mathematics , mathematical optimization , control limits , evolutionary biology , biology , operating system
The economic-statistical design of the synthetic np chart with estimated process parameter is presented in this study. The effect of process parameter estimation on the expected cost of the synthetic np chart is investigated with the imposed statistical constraints. The minimum number of preliminary subgroups is determined where an almost similar expected cost to the known process parameter case is desired for the given cost model parameters. However, the available number of preliminary subgroups in practice is usually limited, especially when the number of preliminary subgroups is large. Consequently, the optimal chart parameters of the synthetic np chart are computed by considering the practical number of preliminary subgroups in which the cost function is minimized. This leads to a lower expected cost compared to that of adopting the optimal chart parameter corresponding to the known process parameter case.