Lean Six Sigma is a method for improving how work gets done, formed from two older approaches that answer different questions. Lean, developed at Toyota, asks where time and effort go without producing anything the customer values. Six Sigma, developed at Motorola, asks why results vary and how to bring that variation under control. Used together they address both the speed of a process and its reliability.
The distinction matters in practice. A process can be fast and unpredictable, or consistent and slow; each fails the customer differently. Lean tools such as value stream mapping and waste elimination shorten the path from request to delivery. Six Sigma tools such as control charts and capability studies establish whether a process can meet its requirement at all, and hold it there once it does.
Improvement projects follow a defined sequence rather than proceeding by intuition. DMAIC — define, measure, analyse, improve, control — structures work on an existing process: each phase has an exit condition, and the control phase exists because gains that are not held are not gains. Where a process or product does not yet exist, Design for Six Sigma takes its place.
Practitioner competence is described in belt levels, a convention borrowed from martial arts. A Yellow Belt contributes to projects and handles simple problems locally; a Green Belt leads projects within their own area; a Black Belt leads complex, cross-functional work and coaches others; a Master Black Belt is responsible for the programme rather than individual projects. The levels describe demonstrated capability, not attendance.
The method is not confined to manufacturing, where it began. Banking, healthcare, logistics and public administration all run processes with queues, handoffs, rework and variation, and the same tools apply — Lean office is the name usually given to that application. What changes is the data available and the pace of the work, not the underlying logic.
What Lean Six Sigma is not is a toolkit applied in isolation. Sustained results depend on people close to the work having the authority to change it, on management asking about process rather than only outcomes, and on measurement that is honest about the current state. Organisations that adopt the tools without those conditions typically see initial gains that fade — a pattern common enough to have its own literature.
