A process capability analysis can best be used to

Process capability analysis evaluates how well a process can produce output within specified limits.

It measures the inherent variability of a process relative to its specification limits.

This analysis is valuable for comparing the capabilities of different processes or equipment to ensure they meet required specifications.

It helps in selecting the most appropriate process or equipment by providing quantitative data on their performance.

References: ASQ's "Certified Quality Engineer Handbook" outlines the use of process capability analysis for comparing processes and equipment.