Proposed control charts in case of asymmetric distributions.

A Shewhart control chart that used to monitor product quality by modern manufacturing and service organizations based on assumption of normal distribution, and is not appropriate for skewed distribution. In this paper, we propose an X ¯ –chart for monitoring the process variability based on Johnson family to design robust control charts for skewed distribution. The applied study shows that the performance of the proposed control charts when compared before using Johnson transformation have good properties, and efficient control limits and flexible. [ABSTRACT FROM AUTHOR]