基于路径图的多元统计过程诊断

针对多元统计过程控制图中失控信号的诊断问题，提出了基于路径图的多元统计过程诊断方法.利用路径图给出的变量之间定量化的因果关系，对所有变量分别建立对应的线性回归方程，以得到联立方程模型.通过联立方程模型建立了统一的T2统计量分解方式，并构建了分解式中所有分解项的判定界限，将其作为判定引起失控信号产生的根本原因的标准.通过对三元系统仿真，验证了其有效性.

Multivariate Statistical Process Diagnosis Based on Path Diagram

In view of the diagnosis of out of control signals in multivariate statistical process control charts, a method of multivariate process diagnosis based on path diagram was proposed. Utilizing the quantitative causation among variables given by the path diagram, a simultaneous equation model could be obtained by establishing the linear regression equations for all variables independently. Then, the simultaneous equation model was applied to derive a uniform decomposition for T2 statistic. And the control limits for all decomposition terms were given as the standards of judging the root causes contributing to the out of control signals. Simulation studies for a system consisting of three variables were carried out to demonstrate that the proposed method is reasonable.