for quality characteristic value in the normal distribution, a control diagram is done by using statistical method.
对服从正态分布的质量特性值,用统计的方法构作控制图;
if quality characteristic value is not in the gauss distribution, clustering method is used to draw a control diagram.
对不服从正态分布的质量特性值,用聚类方法构作控制图。
due to the existence of uncertainty sources(disturbance), there is a variation or excursion for the quality characteristic value from the target value.
各种波动源(干扰)的存在,致使产品输出质量特性值发生变异或者漂移。