Problem of setting control limits in control charts is solved in many publications (from standards to articles and books). Algorithm of setting control limits in these publications does not distinguish between autocorrelated and nonautocorrelated data. It lies in excluding of subgroups that give the âout of controlâ signal from control limits computation (after revealing the existing assignable causes and realization of the corrective action). This algorithm is not wholly suitable for autocorrelated data.
This paper deals with the idea mentioned above in more detail and the proposal of methodology for setting control charts when data are autocorrelated will be applied to the selected parameter of the blast furnace process.
Keywords: Control chart; outliers analysis; setting control limits; time series analysis