Improving a Process

David and Sarah Kerridge

There is not one way to improve a process, but many. These are

not alternatives. Used with understanding, all contribute to the

continual improvement of every process, and the whole system.

Each makes other methods more effective, and so they should be

used together. To illustrate this, we concentrate on the

practical problems of using the Deming Cycle, and show how other

actions help it work.

NB Deming called the cycle the Shewhart cycle: others call

it the PDSA cycle, and the Japanese call it the Deming

Wheel. It was certainly given its present form by Deming, so

it seems fair to name it after him.

A unified approach

This combined and unified approach to improvement is typical of

the Deming Philosophy. Instead of learning one technique, and

applying it as much as we can, we take a system view.

This fits in with the way we tackle anything complicated. An

automobile is simple compared to most processes. If we want it to

run well, we do not spend all our time on the electrics, and

ignore the fuel supply, or concentrate on the tyres and forget

the brakes. If there is a break-down, it probably affects just

one part, and naturally we find out which, and work on that

first. But for trouble-free motoring, we make sure that all the

essential parts are regularly serviced. We do not wait for

something to go wrong.

Seven ways to improve a process

We express these as a list of actions and questions. Any one may

produce dramatic improvement on its own. For example, improvement

in the measurement process, even though it does not directly

affect the process, may reduce tampering. More often it is the

interaction between these approaches that produces results. What

is more, we must see the investigation of this one process as

part of the transformation of the whole organisation.

Without overall change, it is hard to improve an individual

process, and the improvement, even if we achieve it, seldom

lasts. But equally, working on a process can make some of the

ideas behind overall transformation more concrete, and fix them

in people's minds.

1 Study the customers' needs. Is the output of our process the

most helpful that could be given to them? Is it causing

problems in a later process? There is no point in improving a

process until you know what a good result really means.

2 Flow-chart the process. Are there unnecessary stages, or

examples of rules 2-4 of the funnel? Have you identified all

the internal and external customers and suppliers? Do you

listen to them?

3 Improve the training of the process operators. Introduce

Operational Definitions.

4 Study ways to measure outputs and inputs. What measures are

most relevant to the success of the process? Check that the

measurement processes are under statistical control before

attempting to use the measurements to study the process.

5 Reduce variability of the inputs. The inputs include every way

in which the rest of the system affects the process. Can you

reduce the numbers of internal or external suppliers to the

process? Do the suppliers understand your process?

6 Plot the outputs and inputs on SPC charts. Remove special

causes. Eliminate tampering.

7 Collect suggestions for improving the process, and test them

using the Deming Cycle.

There are more ways to improve a process, but these are enough

to make the point. The Deming Cycle relies on checking the

results of a change, using measurement. When the process itself

varies less, and measurements on it are more accurate, it is easy

to see the effect of a change. Besides which, the understanding

of the process which comes from all these different ways of

studying it will suggest changes that should be tried.

What should we do first?

For an individual process that has not been studied before, the

order given above is reasonably good. This does not mean that we

finish one before going on to the next: we usually do several at

the same time.

Even if the process suffers from a major problem which must be

solved, do not neglect the general, systematic, approach. There

is a good reason for this. If the cause of the problem had been

obvious, such as something broken, it would have been put right

immediately. So we expect the investigation to take time.

Occasionally a problem disappears, still unexplained, as a part

of overall improvement. Most often the cause is easier to trace

when systematic improvement is under way.

It is so natural to rely on trouble-shooting that we give some

examples of this. One process had consistently bad results over

many years. Every so often a trouble-shooting team went out from

head office, found a problem and fixed it: but things were soon

just as bad as before. Then control charts were plotted for

inputs and outputs, and the process improved without further

specific action. In another case, a long standing problem dis-

appeared after a change to a single supplier.

Applying the Deming Cycle

Because it relies on stability, and on good measurements, the

Deming Cycle is most effective when the other six approaches to

systematic improvement are under way. It is not a recipe, but a

system: in other words, it does not tell us what to do, but how

make what we choose to do systematic and effective.

We must first decide on which change we should try. This is part

of the "Plan" stage of PDSA. There will usually be plenty of

ideas to choose from, provided everyone understands that learning

about the process is more important than guessing the "right"

answer. So no-one is blamed for making the wrong guess. After

all, even if a change does make things worse, it will suggest

ways to make things better.

We can only test one change at once, so if there are many

suggestions, we need ways to choose between them. Here are some

key questions:

1 Can it be tested on a small scale?

2 Will the effect be seen reasonably quickly?

3 Will the effect be easy to measure?

4 Does the test require new measurements, or will existing

measurements be sufficient?

5 Has the measurement already been studied and shown to be

stable?

6 Is the test simple to do?

7 Will it take long to do?

8 Can the test be done without disturbing the ordinary running

of the process?

Obviously if the answer is "yes" to all these questions, the

change should be tried as soon as possible. We will seldom be so

fortunate, but the number of "yes" answers gives a crude order of

priority among different possible changes. Often practical

considerations, like the need to maintain the enthusiasm of the

team, will provide the deciding vote.

There is, however, one general principle which might be

overlooked. In the long run, a change that reduces variation,

without making the average worse, is more desirable than one

which improves the average, leaving the variation as great as

before. This is because reduced variation makes other improve-

ments easier to find.

Be systematic

Once a choice has been made, make sure that you do not waste any

of the information from the experiment. Keep systematic records

of each stage. Do not rely on memory: it plays too many tricks.

Using the Deming Cycle does not just help to improve the

process. It has great educational value for everyone who takes

part in it. It develops team-work. Ideas at the "Plan" stage will

often be wrong, and many cherished ideas disproved. Members of

the team will learn not to trust guesswork, but to use theory,

and yet rely on facts. They will also see the practical value of

theory, measurement and Operational Definitions. These things

will affect their whole attitude to transformation.