Which concept involves reducing variability in processes?

Six Sigma is a methodological approach primarily focused on reducing variability in processes to enhance quality and performance. It employs a data-driven framework to identify and eliminate defects and ensure that processes operate at their optimal capability. The ultimate goal of Six Sigma is to achieve a level of quality where the likelihood of producing defects is extremely low, statistically measured as 3.4 defects per million opportunities.

The emphasis on reducing variability means that Six Sigma seeks to understand and control the causes of variation, which can lead to improved predictability and efficiency within operations. It uses various tools and techniques, including statistical analysis, process mapping, and problem-solving methodologies, to drive improvements and sustain quality over time.

In contrast, while lean management focuses on eliminating waste and improving flow, and quality assurance emphasizes the processes and systems in place to ensure that quality standards are met, both do not specifically target reducing variability to the degree that Six Sigma does. Control charts are tools used within these methodologies to monitor process stability and variability but are not an overarching approach to reducing variability on their own.