Most quality professionals can recite PDCA: Plan, Do, Check, Act. But in many presentations, the four words appear in separate boxes, implying that each phase is an independent event. This simplification hides a deeper truth: “Act” is not a final step; it is a continuous thread running through all stages of PDCA.
Recognizing this embedded nature of the Act component transforms PDCA from a static model into a living feedback loop where learning and adaptation never stop.
The embedded act concept
W. Edwards Deming’s PDCA was never meant to be a one-directional flowchart. It was designed as a cycle of continuous action and reflection.
In ISO 9001:2015, Clause 10 (Improvement) is triggered by outcomes from Clause 9 (Performance Evaluation) and feeds directly into Clause 6 (Planning), illustrating a self-reinforcing loop. Likewise, ISO/IEC 17025:2017 and ISO 15189 both structure their management systems so that planning, execution, evaluation, and improvement interact continuously.
In essence, Act is embedded in Plan, Do, and Check, appearing wherever analysis, adjustment, or decision-making occurs.
In laboratory and industrial settings, this embedded approach to PDCA translates directly into day-to-day decision-making. For instance, during method validation or instrument maintenance, the Act phase is continuously expressed through real-time corrections, calibration adjustments, or procedural modifications based on performance data. Similarly, in quality reviews or management meetings, actions derived from previous findings shape new planning strategies, creating a continuous thread of improvement. Such integration ensures that PDCA remains a practical, living tool rather than an abstract concept confined to documentation.
Classifying actions across PDCA phases
1. Actions for planning and re-planning (Plan phase)
- Risk evaluation: Identify baseline and dynamic risks and opportunities
- Objective setting: Establish measurable, strategic goals
- Resource allocation: Determine personnel, budgets, and timelines
- Method selection: Define operational methods and success criteria
2. Actions for implementation (Do Phase)
- Execution: Implement processes, controls, and methods
- Training & competency: Ensure staff are equipped and competent
- Data collection: Gather process and performance evidence
- Change management: Modify processes when conditions change
3. Actions for verification and review (Check Phase)
- Monitoring and measurement: Track KPIs, calibration, and process data
- Verification: Ensure conformance with planned requirements
- Analysis: Interpret results, identify deviations, and assess trends
- Reporting: Communicate findings for decision and improvement
4. Actions for improvement and adaptation (Formal act phase)
- Corrective and preventive actions: Respond to nonconformities
- Re-planning: Update risks, objectives, and resources
- Standardization: Revise procedures, methods, and training
- Innovation: Introduce new technologies and continual improvement initiatives
The interconnection of actions
| PDCA Cycle Phase | Embedded "Act" Actions | Feeds Into |
| Plan | Risk evaluation, setting objectives, allocating resources | Do + check |
| Do | Implementation, training, data collection, change management | Check |
| Check | Monitoring, verification, analysis, reporting | Act |
| Act (formal) | Improvement actions, re-planning, standardization | Plan |
Figure 1. The PDCA cycle illustrates embedded actions across all phases and integrates sustainability as a core element of continual improvement.
PDCA in ISO standards context
ISO 9001:2015: The structure from planning (Clause 6) to evaluation (Clause 9) and improvement (Clause 10) demonstrates PDCA continuity.
ISO/IEC 17025:2017: Clauses 8.6 (Improvement) and 8.7 (Corrective Action) rely on earlier results from monitoring and risk assessment.
ISO 15189: Quality management is cyclical across all laboratory processes pre-examination, examination, and post-examination driven by embedded action and review.
In each, the QMS acts as the backbone, integrating PDCA and the embedded Act element across all functions.
Benefits of recognizing the embedded act
- Integrate risk-based thinking into everyday decision-making.
- Strengthen data-driven improvement processes.
- Foster a culture of continual learning instead of reactive correction.
- Provide clearer evidence to auditors that improvement is built into all activities.
Moreover, recognizing the embedded Act phase encourages a mindset of shared responsibility across all levels of the organization. Technicians, analysts, and managers all become active participants in identifying, evaluating, and implementing improvements. This collaborative action culture bridges the traditional divide between quality assurance and operations, making continual improvement a collective pursuit rather than a top-down directive.
Continual improvement and sustainability: The emerging focus
The concept of continual improvement is now evolving beyond process efficiency toward sustainability and long-term performance. The forthcoming ISO 9001:2026 revision is expected to emphasize sustainability as a natural extension of continual improvement, encouraging organizations to align their quality objectives with environmental, social, and governance (ESG) principles.
In this emerging framework, actions within the PDCA cycle will not only target technical excellence but will also consider their impact on resource efficiency, energy use, waste minimization, and social responsibility. Every Act decision, whether in planning, implementation, or review, will need to be evaluated for its broader implications on sustainability and resilience.
Lab Quality Management Certificate
The Lab Quality Management certificate is more than training—it’s a professional advantage.
Gain critical skills and IACET-approved CEUs that make a measurable difference.
For laboratories, this means integrating environmental performance metrics (such as energy or water use, reagent waste, and instrument efficiency) alongside analytical and quality indicators. Similarly, management reviews can include sustainability KPIs, linking performance improvement to reduced environmental footprint and operational efficiency.
By embedding sustainability into the PDCA loop, organizations transform continual improvement into sustainable improvement, balancing performance with purpose. PDCA continues to serve as the engine of sustainable quality management, linking operational excellence, environmental stewardship, and organizational resilience. In the years ahead, this alignment will become a defining feature of ISO 9001:2026 and a key differentiator for forward-thinking laboratories.
PDCA as a living system
PDCA is more than four stages—it is an evolving loop of action, feedback, and improvement. Seeing Act as embedded throughout the cycle clarifies the true nature of continual improvement.
When planning, doing, and checking are all infused with deliberate and purposeful actions, organizations embody Deming’s vision of PDCA as a self-sustaining engine of quality, performance, and innovation. However, it is essential that actions remain logical, scientifically or technically sound, and strategically justifiable. They need to be capable of producing a positive outcome or at least providing a clear direction for progress.
Conversely, illogical, unscientific, non-technical, or unstrategic actions can derail even the most robust systems, leading to setbacks or potential devastation. Hence, thoughtful, evidence-based actions form the true foundation of continual improvement and ultimately, overall lab success. PDCA thus remains a timeless model of continual improvement, adaptable to every evolving quality framework.
References
- 1. ISO 9001:2015 Quality Management Systems – Requirements.
- 2. ISO/IEC 17025:2017 General Requirements for the Competence of Testing and Calibration Laboratories.
- 3. ISO 15189:2022 Medical Laboratories – Requirements for Quality and Competence.
- 4. Deming, W.E. Out of the Crisis. MIT Press, 1986.
