控制图要求各个样本中的子样保持同一分布,以保证非系统因素在样本内引起的过程波动最小,同时最大化非系统因素在样本间引起的波动。而当样本中的子样不是同一分布时候。就会导致控制图具有过大的控制线,降低监控的能力。本文旨在分析和比较几种样本内变差的探测方法,并找出在不同情况下最合适的样本内变差探测组合。
Measured data in each sample of control chart are required to maintain similar distribution. This can keep variations-within-sample caused by non-systematic factors minimal, and maximize the varia- tion-between-sample caused by non-systematic factors. If the measured data in each sample do not come from a same distribution, a wider control area and lower detection capability will be resulted. Some kinds of detection methods are analyzed and compared, and the most suitable detection combination for different conditions is proposed.