This paper studies a model for the economic design of an adaptive X¯ chart for short production r... more This paper studies a model for the economic design of an adaptive X¯ chart for short production runs that are subject to the occurrence of assignable causes, which may either increase or decrease the mean of the quality characteristic. At each sampling instance, the probabilities that the process operates under the effect of an assignable cause are updated using Bayes’
This paper develops a model for the analysis and design of a CUSUM chart for monitoring the proce... more This paper develops a model for the analysis and design of a CUSUM chart for monitoring the process mean in short production runs and proposes statistical measures of performance that are appropriate when the process is not operating indefinitely. The model can be used to evaluate the performance of the CUSUM scheme for any given set of chart parameters and
International Journal of Production Research, 2014
ABSTRACT Fully adaptive control charts are efficient statistical process control means to monitor... more ABSTRACT Fully adaptive control charts are efficient statistical process control means to monitor a quality characteristic affecting the outcome of a manufacturing process. Usually, the performance of these adaptive charts is investigated in processes characterised by the possibility of the occurrence of a single assignable cause. However, this assumption is frequently far from reality, because a process shift to the out-of-control condition can be the consequence of several assignable causes, which can occur at the same time or independently. In this paper, we investigate the economic-statistical design of a variable-parameter (Vp) Shewhart control chart monitoring the process mean in the presence of multiple assignable causes. We develop a Markov chain that models the occurrence of several assignable causes leading to progressive process deterioration and calling for different corrective actions. A benchmark of examples has been generated to compare the performance of the Vp control chart with other adaptive control charts and the fixed-parameter control chart. The obtained results reveal the economic superiority of the Vp control chart.
This paper develops a model for the analysis and design of a CUSUM chart for monitoring the proce... more This paper develops a model for the analysis and design of a CUSUM chart for monitoring the process mean in short production runs and proposes statistical measures of performance that are appropriate when the process is not operating indefinitely. The model can be used to evaluate the performance of the CUSUM scheme for any given set of chart parameters and thus allows comparisons with Shewhart charts and the determination of the most suitable monitoring scheme in any particular application. The model is flexible enough to be used when the CUSUM chart is applied with Fast Initial Response, as well as when the setup and the restoration of the process after an alarm are imperfect.
This paper studies a model for the economic design of an adaptive X¯ chart for short production r... more This paper studies a model for the economic design of an adaptive X¯ chart for short production runs that are subject to the occurrence of assignable causes, which may either increase or decrease the mean of the quality characteristic. At each sampling instance, the probabilities that the process operates under the effect of an assignable cause are updated using Bayes’
This paper develops a model for the analysis and design of a CUSUM chart for monitoring the proce... more This paper develops a model for the analysis and design of a CUSUM chart for monitoring the process mean in short production runs and proposes statistical measures of performance that are appropriate when the process is not operating indefinitely. The model can be used to evaluate the performance of the CUSUM scheme for any given set of chart parameters and
International Journal of Production Research, 2014
ABSTRACT Fully adaptive control charts are efficient statistical process control means to monitor... more ABSTRACT Fully adaptive control charts are efficient statistical process control means to monitor a quality characteristic affecting the outcome of a manufacturing process. Usually, the performance of these adaptive charts is investigated in processes characterised by the possibility of the occurrence of a single assignable cause. However, this assumption is frequently far from reality, because a process shift to the out-of-control condition can be the consequence of several assignable causes, which can occur at the same time or independently. In this paper, we investigate the economic-statistical design of a variable-parameter (Vp) Shewhart control chart monitoring the process mean in the presence of multiple assignable causes. We develop a Markov chain that models the occurrence of several assignable causes leading to progressive process deterioration and calling for different corrective actions. A benchmark of examples has been generated to compare the performance of the Vp control chart with other adaptive control charts and the fixed-parameter control chart. The obtained results reveal the economic superiority of the Vp control chart.
This paper develops a model for the analysis and design of a CUSUM chart for monitoring the proce... more This paper develops a model for the analysis and design of a CUSUM chart for monitoring the process mean in short production runs and proposes statistical measures of performance that are appropriate when the process is not operating indefinitely. The model can be used to evaluate the performance of the CUSUM scheme for any given set of chart parameters and thus allows comparisons with Shewhart charts and the determination of the most suitable monitoring scheme in any particular application. The model is flexible enough to be used when the CUSUM chart is applied with Fast Initial Response, as well as when the setup and the restoration of the process after an alarm are imperfect.
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Papers by George Nenes