An American statistician taught Japanese managers to work in a circle. They turned his idea into Plan–Do–Check–Act — and he spent his last years saying they had got the name wrong.
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Ten items. Say your answer out loud before you reveal it.
Read the sentence, guess the meaning of the word in bold, then reveal.
The three words are: hypothesis · feedback · iterate. Read each meaning, say the word, then reveal.
One missing word fits every phrase in the group. Say it, then reveal.
Read each part. After it, answer the quick check from memory, then discuss one question.
In the 1920s, Walter Shewhart was working at Bell Telephone Laboratories in the United States, studying how to make factory products more reliable. The usual way of thinking about production was a straight line: write a specification, produce the product, inspect it at the end.
In a book published in 1939, Shewhart argued for something different: “These three steps must go in a circle instead of in a straight line.” Specification, production and inspection, he explained, were like the steps of science — making a hypothesis, carrying out an experiment and testing the hypothesis.
The book was edited by a 39-year-old statistician called W. Edwards Deming. He was going to carry Shewhart's circle to the other side of the world.
1. What was the usual “straight line” way of thinking?
2. What did Shewhart compare the three steps to?
3. Who edited Shewhart's book?
1. Write a specification, produce the product, inspect it at the end.
2. The steps of science: making a hypothesis, carrying out an experiment and testing it.
3. W. Edwards Deming, then aged 39.
In 1950, Deming taught an eight-day seminar on quality control for Japanese managers and engineers, organised by the Japanese Union of Scientists and Engineers. He turned the straight line of design, produce, sell into a circle by adding a fourth step: redesign through market research. Then round again, and again.
The Japanese called it the “Deming wheel”. Japanese executives then recast it in their own terms as Plan, Do, Check, Act. Nobody knows exactly who did it. As Ronald Moen, who later researched the history of the cycle, wrote: “No one person claimed authorship.”
Together with seven basic quality tools — among them the Pareto chart and the fishbone diagram — PDCA became the foundation of kaizen, the Japanese approach of continuous, step-by-step improvement. They are still used today.
1. How did Deming change the straight line in 1950?
2. Who turned the Deming wheel into PDCA?
3. What did PDCA become part of in Japan?
1. He added a fourth step — redesign through market research — and made it a circle.
2. Japanese executives; no one person claimed authorship.
3. The foundation of kaizen (continuous improvement), together with the seven basic quality tools.
You might expect Deming to be pleased. He wasn't. In his four-day seminars in the 1980s he often warned audiences that the word “check” was wrong, because in English it means “to hold back”. What he wanted was not checking but studying — learning from the results.
In 1990, commenting on a manuscript by Moen and two colleagues, he wrote: “be sure to call it PDSA, not the corruption PDCA.” A year later, shown a chart labelled Plan/Do/Check/Act, he replied: “How the PDCA ever came into existence I know not.” His final version, in 1993, was the Shewhart Cycle for Learning and Improvement: Plan, Do, Study, Act.
Deming died at the end of 1993. Today both names are used, often by people who have never heard of the argument. But the difference matters. “Check” asks: did it work? “Study” asks: what did we learn?
1. Why did Deming dislike the word “check”?
2. What did he want people to call the cycle?
3. What is the difference between checking and studying?
1. Because, he said, in English it means “to hold back”.
2. PDSA — Plan, Do, Study, Act.
3. Checking asks whether it worked; studying asks what you learnt.
Four steps in a circle. Each turn of the wheel tests one small change, and what you learn becomes the plan for the next turn.
A café wants shorter queues at lunchtime. Which step of the cycle is each action?
1. Check — comparing the results with what was expected.
2. Plan — an idea for a change, plus a prediction.
3. Do — a small-scale trial.
4. Act — making a successful change standard.
5. Check — studying what happened — including the surprise.
6. Plan — deciding how you will judge the test, before you start.
The circle stops at Do. Many teams try something and never find out whether it worked.
Too slow for emergencies. In a crisis there may be no time for a careful trial; a faster loop may fit better.
Small tests, big problems. Some changes can't be tested on a small scale — and some results take years to appear.
PDCA is built on predictions: if we change this, that will happen. English uses two simple conditionals — one for things that are always true, one for real possibilities in the future.
Put the verbs in brackets into the correct form.
1. If you (not water) plants, they die.
2. If the new rota (reduce) waiting times, we'll keep it.
3. When you (press) this button, the machine starts.
4. If it rains tomorrow, the outdoor test (be) cancelled.
5. We (not know) whether it works if we don't measure it.
1. don't water (zero)
2. reduces (first)
3. press (zero)
4. will be (first)
5. won't know (first)
You are planning a trial. Complete each prediction in your own words. Possible answers are shown.
1. If we start meetings at 9.30 instead of 9.00,
2. If customers can order online,
3. If the trial doesn't work,
4. When the trial ends,
1. …more people will arrive on time.
2. …the queues might get shorter.
3. …we'll try a different idea.
4. …we'll compare the results with our prediction.
Now tell your teacher about a small change you'd like to try, with three first conditionals: what you'll do, what you predict, and what you'll do if it fails.
Go round the wheel out loud. Choose a task, start the timer, and talk.
Choose a small problem at work, at home or in your town. Talk it through: Plan, Do, Check, Act.
Describe a change that didn't work. How could a small trial have helped?
Deming said “check” was the wrong word. Explain the difference between checking and studying, with an example from your own life.