Cause & Effect Diagrams help you to think through causes
of a problem thoroughly. Their major benefit is that they
push you to consider all possible causes of the problem,
rather than just the ones that are most obvious.
The approach combines brainstorming with use of a type of
Cause & Effect Diagrams are also known as Fish Bone
Diagrams. The box and line can be thought of as the
head and spine of the fish.
How to use tool
Follow these steps to solve a problem with a Cause &
Identify the problem:
Write down the exact problem you face in detail. Where
appropriate identify who is involved, what the problem is,
and when and where it occurs. Write the problem in a box
on the left hand side of a large sheet of paper. Draw a
line across the paper horizontally from the box. This
gives you space to develop ideas.
Work out the major factors
involved: Next identify the factors that may
contribute to the problem. Draw lines off the spine for
each factor, and label it. These may be people involved
with the problem, systems, equipment, materials, external
forces, etc. Try to draw out as many possible factors as
possible. If you are trying to solve the problem as part
of a group, then this may be a good time for some
brainstorming! Using the 'Fish bone' analogy, the factors
you find can be though of as the bones of the fish.
Identify possible causes:
For each of the factors you considered in stage ii,
brainstorm possible causes of the problem that may be
related to the factor. Show these as smaller lines coming
off the 'bones' of the fish. Where a cause is large or
complex, then it may be best to break the it down into
sub-causes. Show these as lines coming off each cause
Analyse your diagram:
By this stage you should have a diagram showing all the
possible causes of your problem. Depending on the
complexity and importance of the problem, you can now
investigate the most likely causes further. This may
involve setting up investigations, carrying out surveys,
etc. These will be designed to test whether your
assessments are correct.
The example below shows a Cause & Effect diagram drawn by
a manager who is having trouble getting co-operation from
a branch office:
If the manager had not thought the problem through, he
might have dealt with the problem by assuming that people
were being difficult. Instead he might think that the best
approach is to arrange a meeting with the Branch Manager.
This would allow him to brief the manger fully, and talk
through any problems that he may be facing.
Cause & Effect diagrams provide a structured way to help
you think through all possible causes of a problem. This
helps you to carry out a thorough analysis of a situation.