Which methodology does Six Sigma primarily use?

The primary methodology used by Six Sigma is DMAIC, which stands for Define, Measure, Analyze, Improve, and Control. This structured, data-driven approach is specifically designed to improve existing processes. Each phase of DMAIC plays a crucial role in systematically identifying problems, measuring process performance, analyzing data to uncover root causes of defects, improving process performance by implementing solutions, and establishing controls to sustain improvements over time.

Defining the problem and project goals provides a clear focus; measuring helps in quantifying the problem; analyzing leads to understanding underlying causes; improving implements changes that enhance performance; and controlling ensures that the improvements are maintained. This methodology effectively guides teams through the problems they encounter and is fundamental to the Six Sigma framework, making it the core element of process improvement initiatives in various industries.

The other options, such as PDCA, DFSS, and SPC, represent useful methodologies and tools used in quality management and process improvement but do not encapsulate the main structured process improvement framework taught in Six Sigma.