Double sampling (X) over bar control chart (DS) which is a Shewhart-type chart can reduce sample size and detect small process shift fast. In real industries, process observations may be interdependent and correlated, and the statistical performance of DS (X) over bar chart for the correlated data need to be re-evaluated. This article constructs the calculations of statistical indices of DS (X) over bar charts for correlation data and performs a comparative study for investigating the performance distinction of DS (X) over bar charts and other Shewhart-type charts. This comparative study indicates that DS -(X) over bar charts are the best choice for monitoring of correlated data.
机构:
Univ South Africa, Coll Sci Engn & Technol, Dept Stat, POB 392 UNISA 0003, Pretoria, South AfricaUniv South Africa, Coll Sci Engn & Technol, Dept Stat, POB 392 UNISA 0003, Pretoria, South Africa