A diagnostics lab finds that one blood sample in twenty arrives with a label that does not match its request form, so the job is to repair a process that already runs. The same company wants a finger-prick kit patients can use at home, so the job is to create something that does not exist yet. The first is a DMAIC project (define, measure, analyze, improve, control); the second is DMADV (define, measure, analyze, design, verify).

Six Sigma gives you two road maps, and choosing the wrong one is an expensive way to learn the difference. This guide sets the phases side by side, follows one DMAIC project and one DMADV project from the first meeting to the last, shows how to pick between them, and then points to the exact places where ASQ's Green Belt and Black Belt Bodies of Knowledge test the distinction. It is about the methods, not an exam-prep course, though anyone studying for a belt will find the last sections useful.
What do DMAIC and DMADV stand for, and what does each one assume?
DMAIC is the improvement road map. Define the problem and the target, measure how the process performs today, analyze the data to find what causes the gap, improve the process by dealing with those causes, and control it so the gain does not leak away. The method assumes that a process exists, that it delivers an output you can measure now, and that its basic design is capable of reaching the goal once its faults are removed.