X- Chart Using ANOM Approach

Abstract

Control limits for individual measurements (X) chart are available in the literature using moving range as an estimate of process standard deviation. This paper presents new control limits for X - chart using analysis of means (ANOM) approach. In deriving the control limits, sample standard deviation is used as an estimate of process standard deviation. The expected length of the interval between existing (old) control limits is compared with the expected length of the interval between new control limits for the same confidence coefficient and recommendations are made to the practitioner when to use the new control limits.