摘要
Crowder在1987年给出了联合单值与两个接连值移动极差控制图的平均链长的计算方法。[1]本文按照类似的方法，建立了两个接连观测值的移动总和与移动极差图的平均链长的公式，对不同的过程平均值和标准差计算其平均链长，并将所得链长同单位和移动极差图的平均链长作比较，结果表明，S-R图的效率或灵敏度大于X-R图。
With computation of the average run length (ARL) achieved by Crowder in 1987, from the charts of combining individual measurement and moving range, establishes a computational formula of ARL in the charts of combined moving sum and moving range,calculates out it's ARL for different process and standard deviation, and compares these with ARL in the charts of the individual measurement and moving range.
