Plan-Do-Check-Act (PDCA)
Apply PDCA cycle for continuous improvement through iterative problem-solving and process optimization.
Description
Four-phase iterative cycle: Plan (identify and analyze), Do (implement changes), Check (measure results), Act (standardize or adjust). Enables systematic experimentation and improvement.
Usage
/plan-do-check-act [improvement_goal]
Variables
- GOAL: Improvement target or problem to address (default: prompt for input)
- CYCLE_NUMBER: Which PDCA iteration (default: 1)
Steps
Phase 1: PLAN
- Define the problem or improvement goal
- Analyze current state (baseline metrics)
- Identify root causes (use
/whyor/cause-and-effect) - Develop hypothesis: "If we change X, Y will improve"
- Design experiment: what to change, how to measure success
- Set success criteria (measurable targets)
Phase 2: DO
- Implement the planned change (small scale first)
- Document what was actually done
- Record any deviations from plan
- Collect data throughout implementation
- Note unexpected observations
Phase 3: CHECK
- Measure results against success criteria
- Compare to baseline (before vs. after)
- Analyze data: did hypothesis hold?
- Identify what worked and what didn't
- Document learnings and insights
Phase 4: ACT
- If successful: Standardize the change
- Update documentation
- Train team
- Create checklist/automation
- Monitor for regression
- If unsuccessful: Learn and adjust
- Understand why it failed
- Refine hypothesis
- Start new PDCA cycle with adjusted plan
- If partially successful:
- Standardize what worked
- Plan next cycle for remaining issues
Examples
Example 1: Reducing Build Time
Example 2: Reducing Production Bugs
Example 3: Improving Code Review Speed
Notes
- Start with small, measurable changes (not big overhauls)
- PDCA is iterative—multiple cycles normal
- Failed experiments are learning opportunities
- Document everything: easier to see patterns across cycles
- Success criteria must be measurable (not subjective)
- Phase 4 "Act" determines next cycle or completion
- If stuck after 3 cycles, revisit root cause analysis
- PDCA works for technical and process improvements
- Use
/analyse-problem(A3) for comprehensive documentation

