DMAIC – or Define, Measure, Analyze, Improve, and Control – is a process used by Six Sigma practitioners to improve existing products or processes. Imagine you are a costume jewelry manufacturer, coating inexpensive silver with thin layers of gold. You import materials and components from China. A small number of components are always defective, but you don’t know how many or how much it is costing. You need to reduce the number of defective units produced.