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Khan et al. presented the results using the approximation for the control chart using a modified exponentially weighted moving average (EWMA) statistic. In this paper, we will correct the results using Monte Carlosimulation. We will show that modified EWMA is more efficient than traditional EWMA in terms of average run length. [ABSTRACT FROM AUTHOR]

A new control chart for a service performance index based upon the proportion of customer complaints using the repetitive sampling scheme is proposed. The control chart coefficients have been estimated for different parametric combinations using different levels of the performance index. The performance of the new control chart is evaluated on the basis of the average run length (ARL) for in-control and shifted processes. A simulation study for estimating three parameters of the proposed control chart is carried out in order to see the performance of the proposed methodology. The proposed control chart performs better than the existing chart in terms of the ARLs. A real-world example from industry has been included for the practical application of the proposed control chart. [ABSTRACT FROM AUTHOR]

In this paper, we propose a mixed control chart to monitor the process quality using attribute data combined with variable data. The proposed control chart proceeds like an np control chart based on the number of nonconforming parts but requires variable data only when the decision is indeterminate. The control coefficients are determined by considering the in-control and the out-of-control average run lengths for various specified parameters. The extensive tables are provided for the industrial use. The advantages of the proposed control chart are discussed over the traditional np control chart. [ABSTRACT FROM AUTHOR]

In this paper, we propose extended exponential weighted moving average (EEWMA) control chart (CC) for the surveillance the process mean using repetitive sampling scheme under the assumption that quality characteristic of a product is a quantitative variable following the normal distribution. Two control limits named as inner and outer control limits of the proposed CC are derived using the in-control process mean and variance. The necessary measures are derived to obtain the process in-control and out-of-control average run length (ARL) and tabulated for different process shifts and smoothing constants. Comparisons are made to check the capability of intended CC with the EEWMA CC and repetitive EWMA CC in term of ARL. It has been observed that the presented CC shows better results in term of early detection of divergence in process mean. A simulation study is carried out to illustrate the performance of the proposed CC. An industrial example has been incorporated for its practical purpose. [ABSTRACT FROM AUTHOR]

In this paper, we propose an attribute np control chart for monitoring the mean lifetime of the products under accelerated life test. The control chart is designed based on a new sampling procedure namely modified multiple dependent state sampling which is a modified version of multiple dependent state sampling methodology. The optimal parameters to construct the proposed chart are determined so that the in-control average run length is as close as possible to the specified average run length. The performance of the proposed control chart is investigated using a simulated data and compared with the performance of existing control charts. [ABSTRACT FROM AUTHOR]

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In this paper, we propose a new variable control chart under type II or failure‐censored reliability tests by assuming that the lifetime of a part follows the Weibull distribution with fixed and stable shape parameter. The purpose is to monitor the mean and the variance of a Weibull process. In fact, the mean and the variance are related to the scale parameter. The necessary measures are given to calculate the average run length (ARL) for in‐control and shifted processes. The tables of ARLs are presented for various shift constants and specified parameters. A simulation study is given to show the performance of the proposed control chart. The efficiency of the proposed control chart is compared with a control chart based on the conditional expected value under type II censoring. An example is also given for the illustration purpose. [ABSTRACT FROM AUTHOR]

Two popular sampling schemes have been used to design control charts by means of a modified exponentially weighted moving average (EWMA) statistic. The structures of the proposed charts, using repetitive group sampling and multiple dependent state sampling, have been presented. The values of average run length have been determined by some specified control chart parameters. The performance of the proposed chart was illustrated via a simulation study. The efficiency of the proposed chart has been compared with the existing one. A practical example based on real data was also given to explain the application of the proposed chart in industry. [ABSTRACT FROM AUTHOR]

We provide the complete design of a hybrid exponentially weighted moving average (HEWMA) control chart for COM-Poisson distribution. The necessary measures of the proposed control chart are given in this manuscript, and the average run lengths (ARLs) are determined through Monte Carlo simulation for various values of specified parameters. The performance of the proposed chart is compared with two existing control charts. The proposed chart is more efficient than these two existing charts in terms of ARLs; application of the proposed chart is described with the help of Montgomery's data (Introduction to Statistical Quality Control, John Wiley & Sons, New York, 2007). [ABSTRACT FROM AUTHOR]

A control chart is an ever-popular tool for monitoring the production process. The early detection of a process shift, if any, is the desire of the quality control personnel. In this article, an effective alternative control charting procedure has been developed for the monitoring of exponentially distributed quality characteristic using the double moving average combined with EWMA statistic. The performance of the proposed control chart is examined for different combinations of the shift constant, the EWMA smoothing parameter, the moving average span, and the target in-control average run lengths. It has been observed that the proposed control chart is more efficient in the detection of process shifts as compared to control chart suggested by Khoo and Wang for the same purpose. The proposed control chart is illustrated for practical usage with the help of a synthetic and a real dataset. [ABSTRACT FROM AUTHOR]

In this paper, the design of a control chart is given using a modified exponentially weighted moving average statistic under the assumption that the quality characteristic of interest follows the normal distribution. The structure of the proposed control chart is developed, and the necessary measures are derived to find the average run length for in-control and out-of-control processes. The efficiency of the proposed chart is compared with two existing control charts in terms of the average run length. The results are explained with the help of industrial example. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new control chart is proposed by using the belief statistic for the exponential distribution. The structure of the proposed control chart is given to measure the average run length for the shifted process. The comparison of the proposed chart is given with the existing charts in terms of the average run lengths, which shows the outperformance of the proposed chart. The performance of the proposed control chart is also discussed with the help of simulated data. [ABSTRACT FROM AUTHOR]

The design of a new mixed attribute control chart adapted to a truncated life test has been presented. It was assumed that the lifetime of a product follows the Weibull distribution and the number of failures was observed using a truncated life test, where the test duration was specified as a fraction of the mean lifespan. The proposed control chart consists of two pairs of control limits based on a binomial distribution and one lower bound. The average run length of the chart was determined for various levels of shift constants and specified parameters. The efficiency of the chart is compared with an existing control chart in terms of the average run length. The application of the proposed chart is discussed with the aid of a simulation study. [ABSTRACT FROM AUTHOR]

The design of a control chart has been presented using a belief estimator by assuming that the quantitative characteristic of interest follows the gamma distribution. The authors present the structure of the proposed chart and derive the average run lengths for in-control and a shifted process. The average run lengths for various specified parameters have been reported. The efficiency of the proposed chart has been compared to existing control charts. The application of the proposed chart is illustrated with the help of simulated data. [ABSTRACT FROM AUTHOR]

An attribute control chart is developed in this manuscript for the Pareto distribution of second kind under a time truncated life test. We assume that the lifetime of the product of interest follows this distribution with known or unknown shape parameter. The performance evaluation of the proposed control chart is studied using the average run length (ARL). The tables are presented for various values of shape parameter, sample size, specified ARL and shift constants. A simulation study is given to demonstrate the performance of the proposed control chart for monitoring of non-conforming items in the industries. [ABSTRACT FROM PUBLISHER]

We propose an exponentially weighted moving average (EWMA) control chart for monitoring exponential distributed quality characteristics. The proposed control chart first transforms the sample data to approximate normal variables, then calculates the moving average (MA) statistic for each subgroup, and finally constructs the EWMA statistic based on the current and the previous MA statistics. The upper and the lower control limits are derived using the mean and the variance of EWMA statistics. The in-control and the out-of-control average run lengths are derived and tabularized according to process shift parameters and smoothing constants. It is shown that the proposed control chart outperforms the MA control chart for all shift parameters. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new S2 control chart is presented for monitoring the process variance by utilizing a repetitive sampling scheme. The double control limits called inner and outer control limits are proposed, whose coefficients are determined by considering the average run length (ARL) and the average sample number when the process is in control. The proposed control chart is compared with the existing Shewhart S2 control chart in terms of the ARLs. The result shows that the proposed control chart is more efficient than the existing control chart in detecting the process shift. [ABSTRACT FROM AUTHOR]

In this article, modified multiple dependent (or deferred) state sampling control charts for the attribute and the variable quality characteristics are presented. The proposed control charts are designed using the symmetry property of the normal distribution. The control chart coefficients are estimated through simulation at different levels of the parameters using the normal distribution. The proposed control chart scheme is evaluated by calculating the in-control average run lengths and out-of-control average run lengths. Tables are constructed for the selection of parameters for different control limit coefficients under several shift levels for the attribute data as well as the variable data. Examples are included for the practical application of the proposed control chart schemes. The proposed control chart scheme is also compared with the existing control charts. It has been observed that the proposed schemes are better in quick detection of the out-of-control processes. [ABSTRACT FROM AUTHOR]

In the present paper, we propose a control chart based on extended exponentially weighted moving average (EEWMA) statistic to detect a quick shift in the mean. The mean and variance expression of the proposed EEWMA statistic are derived. The proposed EEWMA statistic is unbiased and simulation results show a smaller variance as compared to the traditional EWMA. The performance of the proposed control chart with the existing chart based on the EWMA statistic is evaluated in terms of average run length (ARL). Various tables were constructed for different values of parameters. The comparison of the EEWMA control chart with the traditional EWMA and Shewhart control charts illustrates that the proposed control chart performs better in terms of quick detection of the shift. The working procedure of the proposed control chart was also illustrated by simulated and application data. [ABSTRACT FROM AUTHOR]

In this paper, a new variable control chart is proposed using multiple dependent-state repetitive sampling by assuming that the data follows a normal distribution having a symmetry property. Its efficiency will be evaluated in terms of in-control and out-of-control average run lengths. The results showed that the proposed chart is better than the existing variable control chart to detect an early shift in the process. An industrial example is given to illustrate the proposed chart in the industry. [ABSTRACT FROM AUTHOR]

In this manuscript, a variable control chart under the time truncated life test for the Weibull distribution is presented. The procedure of the proposed control chart is given and its run length properties are derived for the shifted process. The control limit is determined by considering the target in-control average run length (ARL). The tables for ARLs are presented for industrial use according to various shift parameters and shape parameters in the Weibull distribution. A simulation study is given for demonstrating the performance of the proposed control chart. [ABSTRACT FROM AUTHOR]