We derive an explicit form for the cumulative distribution function of both the Chan et al. (J. Quality Technol. 20 (1988) 162-175) estimator and the Boyles (J. Quality Technol. 23 (1991) 17-26) estimator of the process capability index Cpm when sampling from a normal distribution.

The attainment of superior quality and reliability in a manufactured product depends upon the existence of a framework integrating an organization’s capabilities in management, technology and information utilization. With respect to information utilization, statistical tools are particularly...