A study of a new process capability index

A new process capability index is proposed that takes into account the location of the process mean between the two specification limits, the proximity to the target value, and the process variation when assessing process performance. The proposed index is compared to other indices on several properties. The proposed index is estimated based on a random sample of observations from the production process when the process is assumed to be normally distributed. The 95% lower confidence limits for the proposed index are derived for given sample sizes and its estimates.