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Sustaining Gains: Handoff, Documentation, and Lessons Learned

How to ensure a Six Sigma project does not regress — updated SOPs, training, audit schedule, reward and recognition, and project closure documentation. It sits in Section VIII (Control) of the 2022 CSSBB Body of Knowledge. See also the CQE page on control plans →

Why gains fade

Once the project team disbands, old habits, staff turnover, undocumented workarounds and drifting equipment pull a process back toward its old performance. Sustaining gains means making the new way the only way and making any drift visible quickly.

The sustain toolkit

Element	What it does
Mistake-proofing	Strongest control: removes reliance on memory and attention.
Updated controlled documents	SOPs, work instructions, specifications and forms revised through document control; old versions withdrawn.
Training and qualification	Everyone affected trained on the new method, with records; built into onboarding for new staff.
Control plan	For each key X and Y: what is measured, how, how often, by whom, limits, and the reaction plan.
SPC and visual management	Control charts and visual displays that show drift early.
Audits	Scheduled checks (e.g. layered process audits) that the new method is actually followed.
Process owner handoff	The process owner formally accepts responsibility for ongoing performance and the control plan.
Reward and recognition	Recognize the team and reinforce the new behaviors.

Worked example: is the gain holding?

Charter goal: coating defect rate ≤ 1.5% (baseline 4.7%) (illustrative) Control-phase monitoring: 12 weeks, p chart on weekly defect rate Weeks 1–12 average: 1.3%; no out-of-control signals; audit findings closed → Goal met and stable: hand off to process owner, keep the p chart and quarterly audits. If week 9 had shown 2 of 3 points beyond 2σ above the centerline: → follow the reaction plan, find the special cause, and extend monitoring before closure.

Project closure

Verify the result: post-improvement capability or defect rate compared with the baseline and the charter goal, using data from a period long enough to show the gain is stable.
Finance validates the realized savings (hard vs soft).
The process owner signs the handoff; the Champion approves closure at the Control tollgate.
Document lessons learned and archive the project file.
Identify replication opportunities: other lines, sites or products where the same solution applies.

The closure package

A typical closure file holds the final charter (with any amendments), before/after data and capability, the control plan, the revised documents and training records, the Finance sign-off, the process-owner handoff signature and the lessons learned. Keeping it complete means a later team can replicate the solution, and an auditor can see why the process changed.

Common exam traps

Training alone is the weakest control. Prefer mistake-proofing and process design; training supports them.
The Black Belt does not own the process after closure. The process owner does.
Closing too early: a few good weeks is not evidence that the gain is sustained; follow the monitoring period in the control plan.

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More: DMAIC overview · Project charter · VOC & CTQ · SIPOC · MSA in DMAIC · Process capability · Data collection planning · Graphical analysis · Root cause analysis · Multi-vari analysis · Hypothesis testing · Regression · DOE · FMEA · Define tollgate · Change management · Financial benefits · Team dynamics · Improve tollgate · Piloting & scaling · Poka-yoke (BB) · Solution selection · Control plan · SPC in DMAIC · Sustaining gains

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