We propose a new statistic to control the covariance matrix of bivariate processes. This new statistic is based on the sample variances of the two quality characteristics, in short VMAX statistic. The points plotted on the ...

No planejamento dos gráficos de controle destinados ao monitoramento da média do processo, assume-se que esta permanece fixa em seu valor-alvo até a ocorrência de uma causa especial, que a desloca. em muitos processos, ...

Combining an EWMA chart with a Shewhart chart is traditionally recommended as a means of providing good protection against both small and large shifts in the process mean. Capizzi and Masarotto have proposed an EWMA chart ...

Traditionally, an (X) over bar -chart is used to control the process mean and an R-chart to control the process variance. However, these charts are not sensitive to small changes in process parameters. A good alternative ...

Statistical process control in mechanized farming is a new way to assess operation quality. In this sense, we aimed to compare three statistical process control tools applied to losses in sugarcane mechanical harvesting ...

In monitoring process parameters, we assume normality of the quality characteristic of interest, which is an ideal assumption. In many practical situations, we may not know the distributional behavior of the data, and ...

Cuando se tiene interés en monitorear pequeños cambios en la variabilidad (o en la media) de un proceso, las cartas tipo EWMA han mostrado ser muy eficientes. Estas cartas, en el caso multivariado, tradicionalmente han ...

Este artigo trata dos gráficos de controle de EWMA e de X-barra utilizados no monitoramento de processos cujas observações podem ser descritas por um modelo auto-regressivo de primeira ordem. Os gráficos são planejados ...

Statistical process control has been widely used in agricultural operations for monitoring and improving process quality. This study aims to evaluate the Shewhart and exponentially weighted moving average (EWMA) control ...