🔄 Lean Architect · Tyshchenko Lean Academy

PDCA / DMAIC

Continuous improvement cycles — from idea to standard

PDCA — The Shewhart–Deming Cycle
The PDCA cycle is the simplest process management algorithm for reaching a goal. A continuous spiral: each cycle lifts performance higher.
P
Plan
Plan the steps to reach the goal
Set a SMART goal. Find the cause of the problem. Plan the steps and the resources. Define how you’ll measure success.
🔧 Tools: Pareto, Ishikawa, SMART, A3
D
Do
Carry out the planned steps
Roll out the solution as a pilot. Collect data. Document what happens — without subjective judgments.
🔧 Tools: time study, checklists, Kanban
C
Check
Compare the result with the plan
Was the goal reached? Where did you deviate from the plan? Analyze the causes of the gaps between actual and plan.
🔧 Tools: OEE, charts, KPI dashboards
A
Act
Take action, standardize
If it worked → standardize and scale. If not → go back to P with what you learned. The cycle repeats.
🔧 Tools: SOP, Kaizen, A3 report
The key to PDCA: It’s not 4 steps — it’s a spiral. Each completed cycle becomes the new baseline for the next one. Kaizen without PDCA is just random improvements.
DMAIC — a more modern PDCA cycle (Six Sigma)
DMAIC is a structured approach to process improvement in the Six Sigma methodology. It’s used when the cause of the problem is UNKNOWN and you need deep data analysis.
D
Define
Define the problem, the goal, the customer. Charter, SIPOC
›
M
Measure
Collect data. Measure the defect rate. Baseline
›
A
Analyze
Find the root causes. Pareto, Ishikawa, 5 Whys
›
I
Improve
Roll out the solution. SMED, Poka-Yoke, 5S, Kanban
›
C
Control
Standardize. SOPs, control charts, monitoring
PDCA vs DMAIC — when to use which
🟢 PDCA 🔵 DMAIC
When to use The cause is KNOWN and the solution is clear — you need a systematic approach The cause is UNKNOWN — you need deep data analysis
Cycle time Weeks to months (Kaizen) Months to a year (complex projects)
Complexity Simple. Works with any team Complex. Needs Black Belts / Green Belts
Focus Action and the improvement cycle Measurement and statistical analysis
How they relate DMAIC = an extended PDCA. Plan→D, Do→MI, Check→A, Act→C. Both end with standardization.
The Lean Architect’s rule: Always start with PDCA. If the cause still isn’t clear after 2 PDCA cycles, switch to DMAIC with full data analysis.
From Shewhart to Six Sigma — 90 years of evolution
1
1930s
Walter Shewhart and statistical quality control
At Bell Laboratories (AT&T), Walter Shewhart develops PDSA (Plan-Do-Study-Act) as an algorithm for a scientific approach to improvement. He was the first to apply statistics to managing industrial processes. Shewhart’s control charts are the grandfather of modern SPC and Six Sigma.
2
1950
W. Edwards Deming brings PDCA to Japan
Deming comes to postwar Japan and teaches Japanese industrialists. He adapts Shewhart’s PDSA → PDCA. The Japanese embrace it as a philosophy, not a technique. The Japanese press called Deming the “father of the Japanese miracle” — he died in 1993 at 93, a legend in his own lifetime.
3
1960s–80s
Toyota — PDCA becomes Kaizen
Toyota builds PDCA into TPS as the core mechanism of Kaizen. Every kaizen burst on a Value Stream Map (VSM) is a small, completed PDCA. Toyota’s A3 report is PDCA on a single sheet. By the 1980s, PDCA is a required element of every Lean program in the world.
4
1987
Motorola — the birth of DMAIC and Six Sigma
Bill Smith at Motorola develops Six Sigma as a quality system aiming for 3.4 defects per million opportunities. Along with Six Sigma comes DMAIC — a structured version of PDCA focused on statistics and measurement. Motorola reported $16 billion in savings over 11 years after adopting it.
5
1995 — Today
GE, Amazon, Ford — DMAIC at scale
Jack Welch launches the largest Six Sigma program in history at GE: $12 billion in savings over 5 years. Amazon uses DMAIC to optimize logistics (Prime delivery). Ford, Boeing, Johnson & Johnson — it’s standard in every large corporation. Today a Six Sigma Black Belt is one of the best-paid certifications in industry.
Fun fact: Deming couldn’t stand the name “Deming cycle.” He insisted it was the “Shewhart cycle” — and that he was only its popularizer, not its author. The modesty of a genius.
Fill in a PDCA plan for a real improvement → AI Serhii will check its logic and completeness
P
PLAN
What are we changing? What’s the goal? What are the steps?
Goal (SMART):
Action steps + owners:
D
DO
What exactly are we rolling out, and at what scale?
C
CHECK
How do we measure the result? Which metrics?
A
ACT
If it worked → standardize. If not → ?