What does the sigma level measure in a process?

The sigma level is a statistical measure that quantifies the capability of a process to perform within specified limits, specifically regarding defect occurrences. It reflects how often defects occur in a structured and systematic manner, indicating the process's overall quality in terms of error rates. A higher sigma level equates to fewer defects per million opportunities, which is a crucial aspect of quality management practices such as Six Sigma.

Understanding this concept is fundamental in quality management as it helps identify areas for improvement in processes by providing a clear metric of current performance levels. Emphasizing the frequency of defects directly correlates with the effectiveness of quality control measures and strategies aimed at enhancing product or service reliability.