Shingo’s Whys

The next logical step in complexity

Published: Thursday, July 2, 2020 - 12:03

Shigeo Shingo is one of my heroes in industrial engineering. He had a great mind that thrived on curiosity. Today I am looking at Shingo’s Whys. This is in contrast to Taiichi Ohno’s 5 Whys method.

Ohno’s 5 Whys method is one of the tools in Toyota Production System to get to the root cause of an issue. When you see a problem, you ask, “Why did that problem happen?” When you get an answer to that question, you then ask, “Why did that problem No. 2 happen?” and so on until you get to the root cause. When you eliminate the root cause, the problem is solved.

This approach assumes a direct and linear cause-and-effect relationship. And depending on the user’s expertise and experience, you can get different results. A tool like 5 Whys is user-dependent and one-dimensional. It is appropriate for necessary causes; it may not be appropriate for sufficient causes. Its usefulness certainly diminishes as complexity increases.

Shingo’s Whys are not in relation to Ohno’s 5 Whys, but another set of questions, known as 5W1H. They are:
1. Who?
2. What?
3. Where?
4. When?
5. Why?
6. How?

These questions are the levers you can push to further the search for answers. It is said that the origin of these questions goes back to the great Aristotle. Another source where the idea of the 5W1H was stated clearly is from Thomas Aquinas: “For in acts we must take note of who did it, by what aids or instruments he did it, what he did, where he did it, why he did it, how and when he did it.”

The idea of 5W1H was also made famous by Rudyard Kipling:
I keep six honest serving-men
(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who.

The usefulness of this simple framework is also illustrated in the Job Methods program from the Training Within Industry initiative:

Shingo viewed these as the five elements of production. He noted them as:
1. What? (object of production)
2. Who? (subject of production)
3. How? (method of operation)
4. Where? (space of production)
5. When? (time of production)
6. Why? (applies to all the five elements noted above)

In a simple example of producing a medical swab, perhaps the five elements of production are:
1. What is to be produced? The medical swab
2. Who is producing it? Machines or workers
3. How are we producing it? The different operations the process goes through from raw materials to the end sterile product
4. Where are we producing it? Space utilization: this includes the storage area at incoming, the QC lab for inspection, the storage area for inventory, the clean room for actual production, and again the storage area at the end.
5. When? This includes the duration and timing.

Shingo teaches us to ask “Why?” to each of the five elements of production (Shingo’s Whys):
1. Why do we need this object?
2. Why do we require this subject?
3. Why use this kind of method?
4. Why this kind of space utilization?
5. Why this kind of time?

He brilliantly explained: “The five elements of production just make up the status quo. If we want to improve the present situation, we must direct the question ‘Why?’ at each one of those elements repeatedly and relentlessly.”

The obvious question this would lead to is whether we can ask a “why” question to the “Why?” itself. I will leave this question for the reader to ponder. The questioning with “Why?” gets to the actual purpose behind the reasoning or rationale of a decision. It is an effective way to get to meta-analysis, a second-order activity.

Final words

Shigeo Shingo learned the ideas of making improvements from another giant, Lillian Gilbreth. Shingo learned from Ken’ichi Horigome, who learned from Jiro Kakuda. Kakuda learned the concepts and techniques of improvement at Gilbreth’s institute in the United States. Shingo wonderfully summarized the Gilbreth approach as (the emphasis is mine):
1. Analyze the facts in detail.
2. Pursue work goals by asking the question “Why?” at least three times.
3. Bear in mind that there are several means to any one goal.
4. Identify the “one best way” to perform the task in the present circumstances.

A keen student of the Toyota Production System can identify the inspirations of continuous improvement in the steps detailed above.

I will finish with wonderful words of wisdom from Shingo,
“Time is merely a shadow of motion. Supervisors frequently put pressure on plant workers to speed up their work, to get jobs done more quickly. Yet simply working faster—without improving the motions that take up the time—will not speed things up in the final analysis. Time is merely a shadow of motion, and no matter how much we may complain about shadows, nothing will happen unless we deal with the substance—motion—that throws the shadow.”

Stay safe and always keep on learning…

First published June 7, 2020, on Harish’s Notebook blog.

About The Author

Harish Jose

Harish Jose has more than seven years experience in the medical device field. He is a graduate of the University of Missouri-Rolla, where he obtained a master’s degree in manufacturing engineering and published two articles. Harish is an ASQ member with multiple ASQ certifications, including Quality Engineer, Six Sigma Black Belt, and Reliability Engineer. He is a subject-matter expert in lean, data science, database programming, and industrial experiments, and publishes frequently on his blog Harish’s Notebook.