variable sampling
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Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 159
Xuelong Hu ◽  
Suying Zhang ◽  
Guan Sun ◽  
Jianlan Zhong ◽  
Shu Wu

Much research has been conducted on two-sided Exponentially Weighted Moving Average (EWMA) control charts, while less work has been devoted to the one-sided EWMA charts. Traditional one-sided EWMA charts involve resetting the EWMA statistic to the target whenever it falls below or above the target, or truncating the observations above or below the target and further applying the EWMA statistic to the truncated samples. In order to further improve the performance of traditional one-sided EWMA mean (X¯) charts, this paper studies the performance of the Modified One-sided EWMA (MOEWMA) X¯ charts to monitor a normally distributed process. The Monte-Carlo simulation method is used to obtain the zero- and steady-state Run Length (RL) properties of the proposed control charts. Through extensive simulations and comparisons with other charts, it is shown that the proposed MOEWMA X¯ charts compare favorably with some existing competing charts. Moreover, by attaching the variable sampling intervals (VSI) feature to the MOEWMA X¯ charts, it is shown that the VSI MOEWMA charts outperform the corresponding charts without the VSI feature. Finally, a real data example from manufacturing process shows the implementation of the proposed one-sided charts.

2021 ◽  
Vol 1 (1) ◽  
pp. 45-57
Dewi Puspaningtyas Faeni ◽  
Ratih Puspitaningtyas ◽  
Ravindra Safitra ◽  

Abstract Purpose: This study examined variables aimed at examining work-life balance, Career Improvement and work pressure towards productivity. Research methodology: This study was conducted on employees of LSP P3 PIB, examining of what is the correlation between the correlations of the three exogenous variable factors towards productivity as an endogenous variable. Sampling in this research was calculated using the Slovin formula using the Simple Random Sampling. The Respondents are 105 people, rounded up to 100 people. The respondents were employees of LSP P3 PIB. The methodological technique used for data collection is by distributing questionnaires from the firsthand source or Primary Data. The statistical test tool used is SmartPLS 3. Results: The conclusion of this study demographically, the majority of the respondent are women. The outcome of this research is that work-life balance (0.351) positively and significantly affects productivity, while Career (0.309) has a significantly positive effect, and stress (0.294) has a significant positive effect on productivity. Limitations: The limitation is that it is only conducted on variables that are studied and excluding other external variables with a limited number of respondents in less than one year. Contribution: The organization be more aware of the employees’ working engagement by supporting the employees to adjust their work schedule that is Work-Life Balance for their productivity.

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Li Xue ◽  
Zhen He

The control chart and the maintenance management need to control process quality and reduce out-of-control cost. They are two key tools in the production process; however, they have usually been analyzed separately in the literature. Moreover, the existing studies integrating these two concepts suffer from three significant drawbacks as follows: (1) using control charts with fixed parameters to monitor the process, so that the small and middle shifts are detected slowly; (2) monitoring the mean and standard deviation separately, whereas, in real condition, the mean and standard deviation should be monitored simultaneously; (3) quality loss function is not usually used to design economic model, which leads to a large social quality loss in the monitoring process of control chart. To eliminate these weaknesses, the economic design of the exponential weighted moving average (EWMA) control chart with variable sampling intervals (VSI) for monitoring the mean and standard deviation under preventive maintenance and Taguchi’s loss functions is proposed. The optimal values of the parameters are determined to minimize the loss-per-item in an average cycle process. In addition, a genetic algorithm is used in a numerical example to search for the optimal values of the parameters. According to the sensitivity analysis, the effect of the model parameters on the solution of the economic model is obtained. Finally, the comparison study shows that the VSI EWMA control charts designed by the joint economic model are expected to reduce loss.

Muhammad Zeeshan Zahir ◽  
Jun-Hyung Lim ◽  
Seung-Yoon Noh ◽  
Se-Jin Yook

2021 ◽  
Constantin Ahlmann-Eltze ◽  
Wolfgang Huber

The count table, a numeric matrix of genes × cells, is a basic input data structure in the analysis of single-cell RNA-seq data. A common preprocessing step is to adjust the counts for variable sampling efficiency and to transform them so that the variance is similar across the dynamic range. These steps are intended to make subsequent application of generic statistical methods more palatable. Here, we describe three transformations (based on the delta method, model residuals, or inferred latent expression state) and compare their strengths and weaknesses. We conclude with an outlook on future needs for the development of transformations for single-cell count data.

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