Six Sigma provides the opportunity and discipline to eliminate mistakes, improve morale, and save money (Henderson and Evans, 2000). Doing things right in the first time and keeping them consistently is the only idea behind Six Sigma. Its fundamental objective is to achieve customer satisfaction...

The quality level measurement of a given process is essential to some phases of six sigma methodology. So far, different indicators have been applied to estimate the capabilities of a process such as classic yield, defect per unit, sigma quality level and rolled throughput yield.