Open AccessMONITORING PROCESS LOCATION AND DISPERSION SIMULTANEOUSLY USING A CONTROL REGION
Author(s) -
LiPang Chen,
Syamsiyatul Muzayyanah,
SuFen Yang,
Bin Wang,
Ting-An Jiang,
Shengjin Gan
Publication year - 2022
Publication title -
dyna
Language(s) - English
Resource type - Journals
eISSN - 1989-1490
pISSN - 0012-7361
DOI - 10.6036/10115
Subject(s) - ewma chart , control chart , control limits , kernel density estimation , statistical process control , statistics , statistic , dispersion (optics) , x bar chart , computer science , process (computing) , chart , process control , control theory (sociology) , mathematics , control (management) , artificial intelligence , physics , estimator , optics , operating system
Control charts are effective tools for detecting out-of-control conditions of process parameters in manufacturing and service industries. The development of distribution-free control charts is important in statistical process control when the process quality variable follows an unknown or a non-normal distribution. This research thus proposes to use a distribution-free technology to establish a new control region based on the exponentially weighted moving average median statistic and exponentially weighted moving average interquartile range statistic for simultaneously monitoring the process location and dispersion and further sets up a corresponding new control chart. We compute the out-of-control average run length to evaluate out-of-control detection performance of the proposed control region and also compare the proposed control region with some existing location and dispersion control charts. Results show that our proposed chart always exhibits superior detection performance when the shifts in process location and/or dispersion are small or moderate. The new control region is thus recommended. Keywords: control chart, distribution-free, dispersion and location, EWMA, kernel control region, kernel density estimation.