Improve Phase in Six Sigma


To learn from pilots of the selected solution(s) and execute full-scale implementation.


  • For a quality-improvement project: Tested, robust solutions shown to affect the proven causes (Xs) that affect the critical output (Y)
  • For a Lean project: Documentation on results of the chosen Lean best practice or solution applied (5S, Pull system, Four step rapid set up, etc.)
  • An improved process that is stable, predictable and meets customer requirements

Key steps in Improve

  1. Develop potential solutions. Use the confirmed cause-and-effect relationship (from Analyze) to identify a wide range of potential solutions. This is one step where pushing for creativity is highly desired.
  2. Evaluate, select, and optimize best solutions. Flesh out the solution ideas, develop criteria and evaluate the alternatives, document the results. Be open to altering or combining options to optimize the final selections. If necessary, perform designed experiments to find optimal settings for combinations of factors.
  3. Develop “To Be” value stream map. Revise the existing VSM to reflect what the process will look like after changes are made. Include estimates of time savings, improved quality, and so on.
  4. Develop and implement pilot solution. Write up the tasks to be performed in the pilot solution. Train pilot participants. Document results of pilot along with ideas for improvements.
  5. Confirm attainment of project goals. Compare results to baseline.
  6. Develop and execute full-scale implementation plan.
  7. Prepare for Improve gate review.

Gate review checklist for Improve

  1. Solution development and selection
    • Documentation on alternative solutions considered
    • Data displays, statistical analysis, or documentation on other tools used to develop the solutions
    • List of weighted criteria used to evaluate solution; solution matrix or other display summarizing the evaluation results (should include benefit, effort, cost, ease and timing of implementation, resource requirements, etc.)
    • List of concerns raised by process participants and the process owner, and notes on how those concerns have been or will be addressed
  2. Pilot testing
    • Documentation (including “to be” value stream map) of the redesigned process with changes in process flow highlighted
    • Documentation on communication with process participants, customers, and owners (as appropriate)
    • Data display, statistical analyses or other documentation showing the results of pilot test or simulation
    • Documentation of what was learned from the pilot test and plans for improvement during full-scale implementation
    • Documentation confirming that the pilot solution can achieve project goals (include before/after charts, hypothesis tests, etc.)
  3. Full-scale implementation
    • Documentation of plans you used for full-scale implementation
    • Risk management plans (for avoiding, reducing, or mitigating risks)
    • Plans for addressing regulatory (e.g., OSHA), legal, fiscal, or other business requirements
    • Documentation of results from full-scale implementation (especially data showing stable performance)
  4. Updated charter and project plans
    • Updated project charter, financial benefits, and schedule.


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