Control chart for log-logistic using quantile approach

Abstract

One of the main statistical process control tools is a control chart. The latter constructed under the hypothesis that the quality characteristics processes belong a normal distribution, but in the most real situation, the set of data are not following a normal distribution. Thus, the control limits will give misleading results. Therefore, it is important to use an alternative control chart approach. In this paper, a quantile approach has been discussed to construct the quality control chart for the log-logistic model. Properties of log-logistics and parameter estimation have been considered and compared with the existing control chart. Real data is used to apply the proposed control chart.