【摘要】 最近的理论研究证实了具有可变抽样区间(VSI)的过程控制图和可变样本容量(VSS)控制图比常规控制图(FSSI)能较大地提高控制图的效率。文章假定过程处于统计控制状态的时间t服从负指数分布:f(t)=λe-λt(t≥0),利用Costa的马氏链方法[1],设计具有可变样本容量和抽样区间(VSSI)的中位值(x)和极差(R)图。所设计的控制图较之常规控制图能更快地发现过程的变化,从而大大地降低不合格品数。更多还原

【Abstract】 Recent studies show that the x and R charts with variable sample size and with variable sampling intervals detects process shifts faster than the conventional x and R charts. The paper considers the median and range charts with variable sample size and sampling intervals based on Costa model of x Chart. It is assumed that the amount of time the process remains in control has exponential distribution. The proposed charts are compared with the conventional charts, the variable sample size charts and the variable sampling interval charts in terms of the average time to signal an off target process.更多还原