عنوان مقاله [English]
In statistical quality control, the concentration and dispersion of continuous quality characteristics in a process are usually examined simultaneously with the help of two graphs. In this way, the changes in each will be identifiable simultaneously. Due to the high efficiency of control graphs of mean and standard deviation with double sampling in rapid identification of mean changes and standard deviation of the process, discussion of this category of graphs seems necessary. In this paper, based on the results of designing mean control and standard deviation diagrams with double sampling, mean and control standard deviation diagrams with triple sampling are introduced. Statistical design of mean control and standard deviation diagrams with triple sampling is formulated as an optimization problem and to solve this problem, genetic algorithm is proposed.