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.