An improved control chart structure for process location parameter

The article proposes a Shewhart-type control chart, namely M_t chart, for an improved monitoring of the mean level of a quality characteristic of interest, say Y, in a process. The proposed control chart uses the information on a single auxiliary characteristic, say X, of the process and is based on product-difference-type estimator, say M_t (in fact the spirit is to pool different styles of using information on auxiliary variable(s)). Assuming bivariate normality of the characteristic of interest Y and the auxiliary characteristic X, design structure of the proposed M _t chart is developed and its comparisons are made with those of some existing control charts used for the same purposes. The comparisons reveal an improved performance of the proposed M_t chart relative to its existing counterparts due to suggested merger of different approaches.