Knowledge centre · Process improvement
The DMAIC improvement journey
Understand the phases. Choose tools with purpose.
DMAIC stands for Define, Measure, Analyze, Improve and Control. It provides a structured way to investigate a process problem, address its causes and sustain the improvement. Start with the question each phase must answer, then choose the tools that help you answer it.
This overview includes the tools, measurement concepts and project activities covered in our reference toolset. It is a guide to selection, not a checklist: every project does not need every tool, and some tools can be used in several phases.
What each phase means
DMAIC is a structured method for improving an existing process. Each phase has a specific purpose and an outcome that supports the next phase.
| Phase | Definition | Central question | Expected outcome |
|---|---|---|---|
| Define | Establish the problem to address, why it matters, the project boundaries and the improvement goal. | What problem are we solving? | An agreed problem, scope, requirements and measurable goal. |
| Measure | Establish how the current process performs using clearly defined measures and trustworthy data. | What is happening, and how much? | A reliable baseline of current performance. |
| Analyze | Investigate and verify the causes that explain the gap between current and required performance. | Why is the problem happening? | Evidence-supported causes to address. |
| Improve | Develop, test and implement changes that address the verified causes and improve performance. | What changes will solve the problem? | Implemented solutions with demonstrated improvement. |
| Control | Establish ownership, standards, monitoring and responses to sustain the improved performance. | How will we keep the improvement working? | A process that is maintained, monitored and acted on when performance deteriorates. |
These definitions guide our tool selection: place a tool according to the phase outcome it helps produce. The phases distinguish purposes, not isolated sets of activities. Define may need initial observations and data; Measure establishes a reliable baseline; Analyze uses evidence to explain it. A working document such as a value stream map can begin in one phase and support later phases.
DEFINE
What problem are we solving?
During Define, we establish which problem the project will address and why it matters. We identify the process and people affected, understand the relevant customer or business requirements, and agree on the project’s boundaries. Initial observations, existing data and process maps help make the problem concrete. We then set a measurable improvement goal.
The problem statement describes the gap that needs attention without assuming its cause or prescribing a solution. The scope makes clear where the project begins and ends, what it includes, and what falls outside it. By the end of Define, the team and relevant stakeholders share an understanding of what needs to improve and what success would mean.
Phase outcome: An agreed problem, scope, requirements and measurable goal.
Scope the project and process
Plan and organise the project
Understand customer requirements
Before moving on: review whether the phase outcome has been achieved.
MEASURE
What is happening, and how much?
During Measure, we establish a trustworthy picture of how the current process works and performs. We decide which measures represent the problem, define precisely how they will be recorded, and check whether the measurement method produces sufficiently reliable results. We use suitable existing data or collect new observations across the conditions and time periods relevant to the project.
The resulting baseline shows the size and pattern of the performance gap, including variation over time or between relevant groups. We distinguish observations from assumptions and consider whether the data adequately represents the process. Measure establishes what is happening; it does not yet establish why it happens. This baseline provides the reference against which later improvements will be assessed.
Phase outcome: A reliable baseline of current performance.
Define measures and collect data
Check measurement and data quality
Explore variation visually
Describe location and spread
Assess performance and capability
Before moving on: review whether the phase outcome has been achieved.
ANALYZE
Why is the problem happening?
During Analyze, we investigate why the current process does not achieve the required performance. We develop possible explanations from process observations, the experience of people doing the work, and the measured data. We then examine those explanations using appropriate analysis, additional observations or targeted tests.
A suspected cause is not accepted simply because it appears on a fishbone diagram, receives many votes or is associated with the outcome. We look for evidence that supports the explanation, consider alternative explanations and identify the conditions in which it holds. The purpose is to establish causes that can meaningfully guide improvement, with the strength and limitations of the evidence made clear.
Phase outcome: Evidence-supported causes to address.
Develop and prioritise cause hypotheses
Investigate the process
Investigate relationships in data
Test factors through experiments
Consolidate verified causes
Before moving on: review whether the phase outcome has been achieved.
IMPROVE
What changes will solve the problem?
During Improve, we develop changes that address the causes established in Analyze. We consider alternative solutions against the project’s requirements, practical constraints, likely benefits, costs and risks. The selected changes may involve the way work flows, the equipment or layout, operating conditions, responsibilities or working methods.
Where appropriate, we test changes through experiments or a pilot before wider implementation. We decide in advance how success will be measured and compare the results with the baseline and improvement goal, taking variation and unintended effects into account. We refine the solution when necessary, implement the effective changes and prepare the standards, monitoring and responses needed to sustain them.
Phase outcome: Implemented solutions with demonstrated improvement.
Improve workplace and process flow
Generate and organise ideas
Select solutions
Design the future process and controls
Test and implement changes
Before moving on: review whether the phase outcome has been achieved.
CONTROL
How will we keep the improvement working?
During Control, we make the improved way of working part of normal operations. We agree who owns the process, document the relevant standards, and ensure that the people doing the work understand their responsibilities. We establish which measures will be monitored, how often they will be reviewed and what signals require action.
A control arrangement includes a response: who investigates a deviation, what action they take and when the issue is escalated. We check that the arrangements work, confirm the improvement with appropriate follow-up evidence and hand responsibility over to the process owner. Project closure does not end continuous improvement; it establishes a maintained process from which further improvement can begin.
Phase outcome: A process that is maintained, monitored and acted on when performance deteriorates.
Document and monitor performance
Establish ownership and review routines
Close and transfer the project
Continue improving
Before moving on: review whether the phase outcome has been achieved.
Reference and next steps
Tool coverage checked against Six Sigma+Lean Toolset: Mindset for Successful Implementation of Improvement Projects, second edition, edited by Stephan Lunau; authors Renata Meran, Alexander John, Olin Roenpage and Christian Staudter. Springer, 2013.
All five DMAIC phases now link to tool guides. Analyze, Improve and Control include developed teaching explanations, worked examples and relevant visuals. Existing Define and Measure guides continue to be expanded to the same depth.
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