Robust X¯ control chart for monitoring the skewed and contaminated process

Abstract

In this paper, we propose the modied Shewhart, the modied weightedvariance and the modied skewness correction methods by usingtrimmed mean and interquartile range estimators to construct the controllimits of robust X¯ control chart for monitoring the skewed andcontaminated process. A comparison between the performances of theX¯ chart for monitoring the process mean based on these three modiedmodels is made in terms of the Type I risk probabilities and the averagerun length values for the various levels of skewness as well as dierentcontamination models.