Cause and Effect Analysis/ Fish-Bone
Model
Cause and Effect Analysis gives a person
a useful way of doing problem analysis. This diagram-based technique, pushes a
person to consider all possible causes of a problem, rather than just the ones
that are most obvious.
Cause and Effect Analysis was devised by
professor Kaoru Ishikawa, a pioneer of quality management, in the 1960s. The
technique was then published in his 1990 book, "Introduction to Quality
Control." The diagrams that you create with Cause and Effect Analysis are
known as Ishikawa Diagrams or Fishbone Diagrams (because a completed diagram
can look like the skeleton of a fish). Cause and Effect Analysis was originally
developed as a quality control tool, but you can use the technique just as well
in other ways.
For instance, one can use it to:
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Discover the root cause of a problem.
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Uncover bottleneck in the
processes.
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Identify where and why a process isn't
working.
There are four steps to using Cause and
Effect Analysis.
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Identify the problem.
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Work out the major factors involved.
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Identify possible causes.
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Analyze your diagram.
Steps to solve a problem with Cause and
Effect Analysis/ Fish-Bone model:
Step 1: Identify the Problem
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First, write down the exact problem one
is facing. Where appropriate, identify who is involved, what the problem is,
and when and where it occurs.
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Then, write the problem in a box on the
left-hand side of a large sheet of paper, and draw a line across the paper
horizontally from the box. This arrangement, looking like the head and spine of
a fish, gives space to develop ideas.
Example:
In this simple example, a manager is
having problems with an uncooperative branch office.
Figure 1 – Cause and Effect Analysis
Example Step 1
Figure-1
Tip 1: Some
people prefer to write the problem on the right-hand side of the piece of
paper, and develop ideas in the space to the left. Use whichever approach you
feel most comfortable with.
Tip 2: It's
important to define the problem correctly. Look at the problem from the
perspective of Customers, Actors in the process, the Transformation process,
the overall World view, the process Owner, and Environmental constraints.
By considering all of these, one can
develop a comprehensive understanding of the problem.
Step 2: Work Out the Major Factors
Involved
Next, identify the factors that may be
part of the problem. These may be systems, equipment, materials, external
forces, people involved with the problem, and so on.
Example:
The manager identifies the following
factors, and adds these to his diagram:
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Site.
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Task.
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People.
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Equipment.
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Control.
Figure 2 – Cause and Effect Analysis
Example Step 2
Step 3: Identify Possible Causes
Now, for each of the factors one
considered in step 2, brainstorm possible causes of the problem that may be
related to the factor.
Example:
For each of the factors he identified in
step 2, the manager brainstorms possible causes of the problem, and adds these
to his diagram, as shown in figure 3.
Figure 3 – Cause and Effect Analysis
Example Step 3
Step 4: Analyzing Diagram
By this stage one should have a diagram
showing all of the possible causes of the problem that you can think of.
Depending on the complexity and
importance of the problem, one can now investigate the most likely causes
further. This may involve setting up investigations, carrying out surveys, and
so on. These will be designed to test which of these possible causes is
actually contributing to the problem.
Example:
The manager has now finished his Cause
and Effect Analysis. If he hadn't looked at the problem this way, he might have
dealt with it by assuming that people in the branch office were "being
difficult."
Instead he thinks that the best approach
is to arrange a meeting with the Branch Manager. This would allow him to brief
the manager fully on the new strategy, and talk through any problems that she
may be experiencing.
