Behrooz Khalilloo - Graduate Student, Department of Industrial Engineering K. N. Toosi University of Technology, Tehran, Iran
Hamid Shahriari - Professor, Department of Industrial Engineering K. N. Toosi University of Technology, Tehran, Iran
Emad Roghanian - Associate Professor, Department of Industrial Engineering K. N. Toosi University of Technology, Tehran, Iran

The initial step in statistical analysis is parameter estimation.In univariate analysis, the parameters mean and standarddeviation must be estimated when they are unknown.when outliers exist in data, use of sample mean results inweek estimation. So, estimators which are robust to thepresence of outliers should be used. In this work robust Mestimatorfor estimating those parameters are used. Theperformance of these robust estimators in presence ofoutliers and their effects on process capability indices arestudied. The results indicate that the proposed robustcapability indices perform much better than the existingprocess capability indices.

Process Capability Indices, Robust Estimator, M-Estimator, Univariate