Robustness of R-Chart to Non Normality

Abstract

This study addresses the appropriate d ₃ values for constructing range control charts (R-charts) when the distributions of the processes are the uniform, triangular, exponential, and Erlang. Comparisons of the range charts are based on Type I error probabilities obtained using simulations. The results reveal that inappropriate use of the d ₃ values strongly affected the performance of the R-charts. Practitioners should be more careful in selecting suitable coefficients when using R-charts methods to process data. The distribution of the processes must be examined before the coefficients are chosen.

Keywords:

• d ₃
• False alarm rate (Type I error probability)
• Range control chart

Mathematics Subject Classification:

• Primary 62P30
• Secondary 62F10