In the realm of continuous improvement methodologies, the Control Phase represents the final and arguably most critical stage of the DMAIC (Define, Measure, Analyze, Improve, Control) framework. While many organizations celebrate their gains after implementing improvements, the true test of success lies in maintaining those improvements over time. This is where sustainability measurement plans become indispensable tools for ensuring that process enhancements remain effective and continue delivering value long after the improvement team has moved on to other projects.
Understanding the Importance of Sustainability in Process Improvement
The sobering reality of process improvement initiatives is that studies consistently show approximately 70% of improvements fail to sustain themselves beyond the first year. This alarming statistic underscores why the Control Phase cannot be treated as a mere formality or administrative afterthought. When improvements decay and processes revert to their previous problematic states, organizations lose not only the anticipated benefits but also the investment of time, resources, and organizational energy that went into making those improvements. You might also enjoy reading about Control Phase: Understanding P Chart and NP Chart Usage in Quality Management.
Sustainability measurement plans serve as the guardrails that keep improved processes on track. They provide the structure, metrics, and accountability mechanisms necessary to detect early warning signs of process drift and trigger corrective actions before small deviations compound into significant problems. You might also enjoy reading about Project Closure Checklist: 15 Steps to Complete Before Finishing Your Project.
Core Components of an Effective Sustainability Measurement Plan
Critical-to-Quality Metrics
The foundation of any sustainability measurement plan rests on identifying and monitoring the right metrics. These should directly connect to the critical-to-quality (CTQ) characteristics that matter most to customers and business outcomes. Rather than tracking every possible metric, successful sustainability plans focus on a manageable set of key performance indicators (KPIs) that provide meaningful insight into process health.
Consider a manufacturing process improvement project that reduced defect rates. The sustainability measurement plan might include these specific metrics:
- Defect rate per thousand units (DPTU)
- First-pass yield percentage
- Customer complaint frequency
- Rework hours per production shift
- Cost of poor quality as percentage of revenue
Baseline and Target Values
Effective measurement requires context. Your sustainability plan must document baseline performance levels (where you started), target performance levels (where you aimed to be), and actual achieved performance levels (where you ended up after improvements). This creates a reference framework for ongoing monitoring.
For example, a customer service call center improvement project might document:
Baseline Performance: Average call handling time of 8.5 minutes, customer satisfaction score of 72%, first-call resolution rate of 61%
Target Performance: Average call handling time of 6.0 minutes, customer satisfaction score of 85%, first-call resolution rate of 80%
Achieved Performance: Average call handling time of 6.2 minutes, customer satisfaction score of 87%, first-call resolution rate of 82%
These documented values establish the performance zone that must be maintained through ongoing control activities.
Developing a Practical Measurement Schedule
The frequency of measurement represents a critical decision that balances vigilance against resource constraints. High-risk or high-volume processes typically warrant more frequent measurement, while stable processes with lower business impact may require less intensive monitoring.
A tiered approach often works well in practice. Using our customer service example, the measurement schedule might look like this:
Daily Monitoring: Call volume, average handling time (tracked automatically by phone system)
Weekly Monitoring: First-call resolution rate, customer satisfaction scores from automated surveys
Monthly Monitoring: Detailed quality audits of recorded calls, trend analysis of all key metrics, review of control charts
Quarterly Monitoring: Comprehensive process capability analysis, correlation studies between metrics, management review sessions
This structure ensures that critical metrics receive constant attention while more comprehensive analyses occur at appropriate intervals.
Statistical Process Control Tools
Statistical process control (SPC) charts represent one of the most powerful tools available for sustainability measurement. These visual tools help distinguish between normal process variation and signals that indicate genuine process changes requiring intervention.
Control Charts in Action
Let us examine a practical example from a healthcare setting where a hospital implemented improvements to reduce patient wait times in the emergency department. Their sustainability measurement plan included an X-bar and R chart tracking average wait times.
The control chart displayed data points for 25 consecutive weeks following improvement implementation. The center line represented the process mean of 42 minutes, with upper control limit at 58 minutes and lower control limit at 26 minutes. For 18 weeks, all data points remained within these control limits, indicating a stable process. However, in weeks 19 through 21, three consecutive points appeared above 52 minutes, trending toward the upper control limit.
This pattern triggered an investigation that discovered two contributing factors: increased patient volume due to seasonal flu and temporary staffing shortages. The team implemented corrective actions including adjusting staffing schedules and activating their surge capacity protocol. Subsequent measurements showed the process returning to statistical control, with wait times stabilizing around the target mean.
Response Plans and Accountability Structures
A measurement plan without clear response protocols amounts to observation without action. Your sustainability plan must specify exactly what happens when measurements indicate problems, who has responsibility for taking action, and what timeline applies for responses.
Creating Effective Response Protocols
Response plans typically establish escalation levels based on the severity of process deviations. A manufacturing operation might structure responses this way:
Level 1 Response (Minor Deviation): Single data point exceeds control limits but no pattern evident. Action: Line supervisor investigates within four hours, documents findings, implements correction if cause identified. Escalate to Level 2 if issue persists.
Level 2 Response (Moderate Deviation): Two consecutive points exceed control limits or clear trend toward limits observed. Action: Department manager and process owner conduct root cause analysis within 24 hours, implement corrective action plan with defined timeline, increase monitoring frequency temporarily.
Level 3 Response (Major Deviation): Process capability falls below acceptable threshold or customer impact occurs. Action: Cross-functional team convenes within 48 hours, executive sponsor notified, comprehensive analysis conducted, improvement project may be reinitiated if necessary.
Documentation and Knowledge Transfer
Sustainability extends beyond the immediate team that implemented improvements. Process knowledge must be captured in accessible documentation and transferred to all individuals who interact with the improved process. This includes standard operating procedures, training materials, visual management tools, and quick reference guides.
A food processing facility that improved sanitation procedures created a comprehensive documentation package including updated standard work instructions with photographs, a training checklist for new employees, visual cues posted at work stations, and a digital repository of all control phase materials accessible to supervisors and quality personnel.
Technology-Enabled Sustainability
Modern organizations increasingly leverage technology platforms to automate data collection, generate real-time alerts, and streamline reporting processes. Dashboard applications can display current performance against targets, highlight metrics requiring attention, and provide drill-down capabilities for deeper analysis.
However, technology should enable rather than replace human judgment. Automated systems excel at capturing and presenting data, but experienced practitioners must still interpret that data, investigate anomalies, and determine appropriate responses.
Continuous Review and Refinement
Sustainability measurement plans themselves require periodic review and adjustment. Business conditions change, customer requirements evolve, and processes mature over time. What constitutes appropriate control at project completion may need modification six months or a year later.
Schedule formal reviews of your sustainability measurement plan at predetermined intervals. These reviews should evaluate whether monitored metrics remain relevant, whether measurement frequency remains appropriate, whether control limits need adjustment based on improved process capability, and whether response protocols proved effective when triggered.
Building a Culture of Sustained Excellence
The most successful organizations recognize that sustainability transcends any individual measurement plan. It reflects an organizational culture that values continuous improvement, holds people accountable for maintaining gains, celebrates sustained performance, and views control activities as essential rather than burdensome.
Leadership plays a crucial role in establishing and reinforcing this culture. When executives regularly review control metrics, ask informed questions about process performance, and visibly support response activities when problems emerge, they signal that sustainability matters. Conversely, when control phase activities receive minimal attention or resources, the message that improvements are optional rather than essential echoes throughout the organization.
Measuring the Success of Your Measurement Plan
How do you know whether your sustainability measurement plan is working? Several indicators provide insight: improved processes maintain performance at or above target levels over extended periods, early detection of problems prevents customer impact, response protocols activate appropriately when triggered, process owners demonstrate ownership and engagement with control activities, and the organization builds capability for sustaining improvements across multiple projects.
Transform Your Organization Through Structured Improvement
Creating effective sustainability measurement plans represents a learnable skill that combines statistical knowledge, practical process understanding, and organizational change management. While this article provides foundational concepts and examples, truly mastering these techniques requires structured training and hands-on practice.
Lean Six Sigma methodologies offer the comprehensive framework necessary for implementing sustainable process improvements in any organizational context. Whether you are beginning your continuous improvement journey or looking to deepen existing expertise, formal training provides the knowledge, tools, and credentials that enable meaningful impact.
Enrol in Lean Six Sigma Training Today and gain the skills needed to not only improve processes but to ensure those improvements deliver value for years to come. Professional certification programs provide structured learning paths covering all DMAIC phases, including the critical Control Phase techniques discussed here. Investment in your professional development translates directly into organizational results as you apply proven methodologies to real business challenges. The difference between temporary gains and lasting transformation often comes down to the knowledge and discipline that structured training provides. Take the next step in your continuous improvement journey and position yourself as a driver of sustainable organizational excellence.
