控制图的报警系统

控制图中的报警系统是由异常点来启动的，而异常点的判断则取决于小概率事件的发生．本文推导出用容量为。的样本均值■和标准差Ｓｎ来估计总体均值和标准差时、点落在控制界限之外的分布．弥补了直接用总体均值ｕ和标准差σ来计算小概率事件所造成的误差．并由此统一了控制图的报警阀值．

The Alarm System of Control Chart

The alarm system of control chart is taken by those extraordinary Points arouning small probability event. In this paper, we give the disterbution density for the point falling outside the upper and lower bound. when we use sam pie average and standard deviation to eatimed totality average and standard devia non. Using this disuterbtion density to calculate event of small probability, we can aviod the error that is caussed by using sample characteristic value for charting but using totality characteristic value for calculating. we unify the boundary val ues of alarm in this paper.