Results 231 to 240 of about 420,626 (277)

A Multivariate Sign EWMA Control Chart

Technometrics, 2011
Nonparametric control charts are useful in statistical process control (SPC) when there is a lack of or limited knowledge about the underlying process distribution, especially when the process measurement is multivariate. This article develops a new multivariate SPC methodology for monitoring location parameters.
Zou, Changliang, Tsung, Fu-gee
openaire   +2 more sources

Ewma charts for multivariate time series

Sequential Analysis, 1997
In this paper a muIt,ivariat.e EWMA chart for time series is introduced. In principle, it is a generalization of the control scheme of Lowry et al. (I992) for multivarite indendent observations. The autocovariances of the EWMA recursion are derived for stationary multivariate time series.
H. G. Kramer, L.V. Schmid
openaire   +1 more source

A spatial rank–based multivariate EWMA chart for monitoring process shape matrices

Quality and Reliability Engineering International, 2019
In this article, we propose a nonparametric EWMA control chart for monitoring the shape matrix of a multivariate process based on a spatial rank test and the exponentially weighted moving average scheme.
Longcheen Huwang, Li-Wei Lin, Cheng‐Ting Yu   +2 more
semanticscholar   +1 more source

A risk-adjusted EWMA chart with dynamic probability control limits for monitoring survival time

Communications in statistics. Simulation and computation, 2019
Developing control charts for monitoring health-care systems has attracted many researchers attention in recent years. Considering the fact that continuous data have more information rather than discrete data, survival time after cardiac surgery is ...
Elahe Tighkhorshid, A. Amiri, Farzad Amirkhani   +2 more
semanticscholar   +1 more source

Studentised residual-based EWMA control charts

2011 2nd International Conference on Artificial Intelligence, Management Science and Electronic Commerce (AIMSEC), 2011
Taking multistage correlation process as objective, this article studies the construction and performance of studentised residual-based EWMA control charts. Residual is used to remove the effect of upstream stages on downstream stages in monitoring multistage cascade processes. In order to overcome the influence of dimension and detect small mean shift
null Zhong Jianlan, null Ma Yizhong
openaire   +1 more source

Designing a Multivariate EWMA Control Chart

Journal of Quality Technology, 1997
A multivariate exponentially weighted moving average control chart can be used to improve the detection of small shifts in multivariate statistical process control. Recommendations are provided for the selection of parameters for such a chart. The recom..
Sharad S. Prabhu, George C. Runger
openaire   +1 more source

Multivariate EWMA Charts with Variable Sampling Intervals

Economic Quality Control, 2009
Summary: The standard multivariate control chart usually employs fixed sample sizes at fixed sampling intervals (FSI) to monitor a process. In this study, a multivariate exponentially weighted moving average (MEWMA) chart with variable sampling intervals (VSI) is investigated.
openaire   +3 more sources

A hybrid EWMA chart using coefficient of variation

International Journal of Quality & Reliability Management, 2019
Purpose The purpose of this paper is to develop a new control chart using two EWMA statistics called the hybrid exponentially weighted moving average (HEWMA) chart to improve the sensitivity of EWMA chart proposed by Zhang et al. (2014).
M. Aslam, S. Gadde, Mansour Sattam Aldosari, C. Jun   +3 more
semanticscholar   +1 more source

An ARL-unbiased thinning-based EWMA chart to monitor counts

Sequential Analysis, 2018
Shewhart control charts are known to be somewhat insensitive to shifts of small and moderate size. Expectedly, alternative control schemes such as the exponentially weighted moving average (EWMA) charts have been proposed to speed up the detection of ...
M. Morais, S. Knoth, C. Weiß
semanticscholar   +1 more source

Combined Shewhart–EWMA control charts with estimated parameters

Journal of Statistical Computation and Simulation, 2010
Shewhart and EWMA control charts can be suitably combined to obtain a simple monitoring scheme sensitive to both large and small shifts in the process mean. So far, the performance of the combined Shewhart–EWMA (CSEWMA) has been investigated under the assumption that the process parameters are known.
CAPIZZI, GIOVANNA, MASAROTTO, GUIDO
openaire   +1 more source