The Control Phase represents the final and arguably most critical stage of the DMAIC (Define, Measure, Analyze, Improve, Control) methodology in Lean Six Sigma. While organizations often celebrate improvements achieved during the Improve phase, these gains can quickly erode without proper control mechanisms in place. Creating effective control plans ensures that process improvements remain sustainable, delivering long-term value and preventing regression to previous performance levels.
Understanding the Control Phase
The Control Phase serves as the guardian of process improvements, establishing systems and procedures that maintain gains achieved through rigorous analysis and implementation. This phase transforms temporary fixes into permanent solutions by institutionalizing new processes, documenting procedures, and implementing monitoring systems that detect deviations before they become significant problems. You might also enjoy reading about Service Industry Control: Sustaining Transactional Process Improvements for Long-Term Success.
Without effective control plans, organizations witness a phenomenon known as process decay, where improved processes gradually revert to their original state. Studies indicate that approximately 70% of process improvements fail within the first year without proper control mechanisms, representing substantial waste of time, resources, and organizational effort. You might also enjoy reading about Visual Controls Implementation: Making Process Status Obvious at a Glance.
Essential Components of an Effective Control Plan
Process Documentation and Standard Operating Procedures
Comprehensive documentation forms the foundation of any control plan. Standard Operating Procedures (SOPs) must clearly outline the new process, including step-by-step instructions, decision points, and responsibilities. These documents serve as reference guides for current employees and training materials for new team members.
Consider a manufacturing facility that improved its quality inspection process, reducing defect rates from 8.5% to 2.1%. The control plan documentation would include detailed inspection criteria, measurement techniques, frequency of checks, and escalation procedures when defects exceed acceptable thresholds.
Statistical Process Control Charts
Statistical Process Control (SPC) charts provide visual representations of process performance over time, enabling teams to distinguish between common cause variation (inherent to the process) and special cause variation (indicating process changes requiring intervention).
For example, a customer service center that reduced average call handling time from 12.3 minutes to 8.7 minutes would implement control charts tracking daily average handling times. The control limits, typically set at three standard deviations from the mean, would alert supervisors when performance drifts outside acceptable ranges.
Key Performance Indicators and Metrics
Identifying and monitoring appropriate Key Performance Indicators (KPIs) enables organizations to track process health systematically. These metrics should directly relate to the critical-to-quality characteristics identified during earlier DMAIC phases.
A hospital emergency department that improved patient wait times from 45 minutes to 22 minutes might track multiple KPIs including average wait time, percentage of patients seen within 30 minutes, staff utilization rates, and patient satisfaction scores. Monthly reviews of these metrics would reveal trends requiring attention.
Developing Your Control Plan: A Practical Example
Let us examine a practical example involving an e-commerce company that improved its order fulfillment process. During the Improve phase, the company reduced order processing errors from 5.2% to 1.3% through workflow redesign and enhanced training programs.
Sample Data Set: Monthly Order Processing Performance
Pre-improvement baseline (six months average):
- Total orders processed: 45,000 per month
- Error rate: 5.2% (2,340 errors)
- Customer complaints: 156 per month
- Processing time: 4.8 hours per 100 orders
- Rework costs: $18,720 per month
Post-improvement performance (first month):
- Total orders processed: 46,500 per month
- Error rate: 1.3% (605 errors)
- Customer complaints: 38 per month
- Processing time: 3.2 hours per 100 orders
- Rework costs: $4,840 per month
Control Plan Implementation
The control plan for this improvement would include the following elements:
Daily Monitoring: Team leaders review error rates from the previous day each morning, investigating any batch with errors exceeding 2%. This immediate feedback loop prevents small problems from escalating.
Weekly Audits: Quality assurance personnel conduct random audits of 5% of processed orders, verifying compliance with new procedures and identifying training opportunities.
Monthly Performance Reviews: Management reviews comprehensive metrics including error rates, processing times, customer satisfaction scores, and cost savings, comparing current performance against established control limits.
Quarterly Process Assessments: Cross-functional teams evaluate the overall process effectiveness, gathering employee feedback and identifying opportunities for further refinement.
Response Plans for Out-of-Control Situations
Effective control plans must include predetermined response mechanisms when processes drift out of control. These response plans outline specific actions, responsibilities, and timelines for corrective measures.
Using our e-commerce example, if the error rate exceeds 2.5% for two consecutive days, the response plan might specify:
- Immediate supervisor notification and investigation initiation
- Temporary increase in quality checks from 5% to 15% of orders
- Review of recent process changes or system updates
- Refresher training for team members if skill gaps identified
- Root cause analysis if elevated rates persist beyond 48 hours
Training and Communication Strategies
Sustainable process control requires ongoing training and clear communication channels. All stakeholders must understand their roles in maintaining process improvements, from frontline employees executing procedures to executives reviewing performance dashboards.
Effective training programs incorporate multiple formats including classroom instruction, hands-on practice, visual aids, and regular refresher sessions. Documentation should be readily accessible, and employees should feel comfortable seeking clarification without fear of repercussion.
Technology Integration in Control Plans
Modern control plans increasingly leverage technology for real-time monitoring and automated alerts. Dashboard software displays key metrics continuously, while automated systems can trigger notifications when performance deviates from established parameters.
Our e-commerce company might implement a dashboard showing real-time error rates, color-coded by severity (green for rates below 1.5%, yellow for 1.5% to 2.5%, red for above 2.5%). Automated email alerts notify supervisors immediately when thresholds are breached, enabling rapid response.
Common Control Plan Pitfalls to Avoid
Several common mistakes can undermine control plan effectiveness. Organizations often create overly complex monitoring systems that become burdensome, leading to abandonment. Conversely, insufficient monitoring fails to detect problems until significant damage occurs.
Another frequent pitfall involves focusing exclusively on lagging indicators (results-based metrics) while neglecting leading indicators (predictive metrics). Balanced control plans monitor both types, providing early warning signals alongside outcome measurements.
Measuring Control Plan Success
Control plan effectiveness should itself be measured and refined over time. Success indicators include sustained performance at improved levels, early detection and resolution of issues, employee adherence to new procedures, and continued stakeholder satisfaction with process outcomes.
For our e-commerce example, control plan success after six months might be demonstrated by error rates consistently maintained between 1.1% and 1.5%, zero instances of problems going undetected for more than 24 hours, 95% employee compliance with new procedures verified through audits, and customer satisfaction scores improved by 23%.
Continuous Improvement Through Control
The Control Phase does not signify the end of improvement efforts but rather establishes a foundation for continuous enhancement. Regular review of control data often reveals additional improvement opportunities, initiating new DMAIC cycles that further optimize processes.
Organizations that embrace this continuous improvement mindset consistently outperform competitors, building cultures where process excellence becomes embedded in daily operations rather than temporary project outcomes.
Conclusion
Creating effective control plans represents the difference between temporary gains and sustained excellence. Through comprehensive documentation, appropriate statistical tools, clear metrics, responsive escalation procedures, and ongoing training, organizations can ensure that hard-won improvements deliver lasting value. The Control Phase transforms process improvement from an event into a sustainable competitive advantage.
Whether you are leading Six Sigma projects within your organization or seeking to enhance your professional capabilities, mastering control plan development is essential for long-term success. The methodologies, tools, and techniques discussed here provide a framework for maintaining process improvements, but practical application requires proper training and guided experience.
Enrol in Lean Six Sigma Training Today to develop the expertise needed to create and implement effective control plans. Professional certification programs provide hands-on experience with real-world case studies, statistical tools, and best practices that transform theoretical knowledge into practical skills. Invest in your professional development and gain the credentials that organizations worldwide recognize as markers of process excellence. Take the first step toward becoming a catalyst for sustainable improvement in your organization by enrolling in comprehensive Lean Six Sigma training today.
