The fourth level focuses on reducing the variation on the stable processes created in the first three levels. The goal is to increase predictability and quality.
The method used at this level is Six Sigma and its corresponding DMAIC approach. Green Belts and Black Belts apply (statistical) techniques and Big Data analytics to realize breakthroughs in quality. They are supported by Yellow Belts and Orange Belts. The focus is on reducing the variation and improving process capability.