retire the pdca wedge

Mike Rother RETIRE THE PDCA WEDGE? 1

FOR

DISCUSSION

Mike RotherJeff UitenbroekAugust 2011

Let’s Retire the PDCA Wedge

Wedge indicating standard orstandardization to hold gains

Improvement

What really keeps performance from slipping back?


SOMETHING TO THINK ABOUTDear Lean Community,We may have a bug in our programming, which is hampering our efforts to achieve continuous improvement.

The PDCA wedge may be a creation of an occasional-improvement mindset, which allows for backsliding between events, instead ofa mindset of continually improving and learning.


IS THE PDCA WEDGE BASED ON A MISCONCEPTION?There is a popular concept that we can utilize standards to maintain a process condition. Such standards are often depicted graphically as a wedge that prevents the process from backsliding.

However, it is generally not possible simply to maintain a level of process performance. Process performance tends to degrade no matter what, even if a standard is defined, explained to everyone, posted and regularly audited.

This is not because of poor discipline, but due tointeraction effects and entropy, which say that any organized process naturally tends to decline to a chaotic state if we leave it alone.

Where did the wedge concept come from?


“Continue the cycle, over and over, with never-ending improvement of quality, at lower and lower cost.”

~ W. Edwards Deming, Out of the Crisis, p181

“Quality of a product does not necessarily mean high quality. It means continual improvement of the process, so that the consumer may depend on the uniformity of a product and purchase it at a low cost.”

~ W. Edwards Deming, 1980

ITʼS PROBABLY NOT FROM DEMING

In the “Act” part of the PDSA cycle, Deming talks about “adopting the change.” That is, if a solution or countermeasure has been successfully tested you might decide to make it permanent.

Deming seems to be talking about standardizing not to prevent slipping back, but simply in regard to putting a tested countermeasure into place.

Deming makes a different statement on the topic of not slipping back: you have to keep turning the PDCA wheel. To maintain gains and uniformity, you have to keep improving.


Consider this: Toyota is achieving quality excellence not because processes are done the same way each time, but because Toyota is striving to achieve the target conditionof processes being done the same way each time.Itʼs a subtle but important distinction.

A “standard” is a description of how a process should operate. Itʼs the intended, normal pattern.

“Standardized work” means, in essence, that a process is actually operating as specified by the standard.

The Toyota way of thinking about many standards is that they are more like something you are striving to achieve. The standard itself doesnʼt make anything happen. Itʼs a definition of where you want to be.

Actual

StandardStandard

Actual

ITʼS PROBABLY NOT FROM TOYOTA


WEDGE WAY versus TOYOTA WAY

What is preventing us from reaching the

target condition?

We need more discipline!

The operatorsare responsible

Management is responsible

We needto maintain

What is thenext step?

Weʼre slippingback

We arenʼtthere yet

Wedge thinkingWhen an abnormality occurs

Toyota thinkingWhen an abnormality occurs

In the wedge way of looking at it we think an abnormality means weʼre slipping back, and itʼs someoneʼs fault.

The Toyota way of thinking turns this around: the abnormality means we have not yet have reached the target condition. There are still obstacles.

Illustration from Toyota Kata, page 115


One reason may be that we think in terms of improvement projects (start, stop, move on), which leads us to an audit & compliance mindset.This thinking may in turn be based on a desire for certainty and misunderstanding of what is ʻscientific.ʼ

WHY DID WE COME UP WITHTHE WEDGE CONCEPT?

What we may think scientific is

What scientific really is

• Quantification and precision• Objective and certain• Reveals what is thereEg: a standard is definitive

• Involves uncertainty,ambiguity & incompleteness

• Never free from error• A process of discovery, via

systematic trial and errorEg: a standard is a hypothesis


Thereʼs no genie who, without us defining the desired standard, is going to make processes work in a way that serves customers with highest quality and lowest cost.

But, likewise, just because weʼve defined a standard does not cause a genie to appear and make things so and hold entropy at bay.

WE NEED A STANDARD, OF COURSE

So a process needs a standard.But how does it work?


A STANDARD IS LIKE A TARGET CONDITIONA standard is an idea of where you want to be

Rather than a backstop, a standard is something you aspire to.Just waiting for deviations and abnormalities and then reacting to them is not enough. Without something to strive for, entropy will set in no matter what you do.

Itʼs here!

Improvement

The standard is not here


The point is that any process is either slipping back or being improved, and the best and perhaps only way to prevent slipping back is to keep trying to move forward - every process every day - even if only in small steps.

The best way to sustain results is to make improvement toward your vision part of normal daily activity.

Fortunately, striving toward a target condition is highly motivating, brings a team together and can be a lot of fun.

BOTTOM LINEThereʼs no steady state


SO LETʼS RETIRE THE WEDGE

Itʼs a lifelong process of striving, for which we are well equipped.We can practice, learn and teach a fundamental way (a kata)

for meeting challenging target conditions along uncertain paths.

retire the pdca wedge

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