Six Sigma, DMAIC and Lean Six Sigma
Six Sigma is a data-driven method for reducing defects and variation in a process. It was introduced at Motorola in the mid-1980s (most sources credit Bill Smith, 1986) and later spread widely through other large companies.
DMAIC
The improvement cycle for an existing process:
| Phase | Purpose | Typical tools |
|---|---|---|
| Define | Problem, customer, scope | Project charter, SIPOC |
| Measure | Baseline performance | Data collection plan, process capability |
| Analyze | Find root causes | Cause-and-effect diagram, statistical tests |
| Improve | Test and implement solutions | Pilots, design of experiments |
| Control | Make the gain stick | Control charts, response plans, process owner hand-over |
DMAIC fits inside the analysis, redesign and monitoring phases of the bpm-lifecycle.
Lean Six Sigma and belts
Lean Six Sigma combines lean (remove waste, speed up flow) with Six Sigma (reduce variation). Practitioner levels use a belt scheme: commonly Yellow, Green, Black and Master Black Belt. Certifying bodies such as ASQ and IASSC each publish their own requirements; ASQ asks for work experience and a project, IASSC is exam-based. See bpm-certifications.
When to use it
Use Six Sigma when you can measure the process and the problem is inconsistency or defects (billing errors, delivery variance). Use Lean when the problem is delay and handoffs. Use business-process-reengineering when the process itself is the wrong design.
Related
kaizen, total-quality-management, theory-of-constraints, BPM hub
Open items
- Origin year and credited inventors vary across sources (1984 concept vs 1986 Motorola); ASQ and IASSC requirements change and should be read from their sites.
Sources
- ASQ, Six Sigma: https://asq.org/quality-resources/six-sigma
- IASSC: https://iassc.org/
- Overview with history: https://en.wikipedia.org/wiki/Six_Sigma