poor communication, incomplete instructions, etc. By analysing the collected
data the vital few causes can be identified and tackled through corrective
steps. Overall human error is bound to reduce if the application is right.
z Pareto principle in conjunction with Brainstorming session can identify the
vital few processes from the numerous steps depicted in flow diagram and
then optimise the process steps through re-engineering.
z Finding out the vital few internal as well as external customers. It is also valid
in finding out the ‘useful many’ customers.
z Analysing the impact of non-conformities on quality, cost, schedule, etc.
z Useful for senior managers: in time management and disposing of pending
jobs.
z In the design of experiments, the selection of experiments to prioritise is done
within the confines of engineering and cost constraints by concentrating on
the ‘vital few’ rather than the ‘trivial many’.
z Process control parameters are monitored and improved by selecting activi-
ties using Pareto diagrams.
z In Hospital and Healthcare services, quality improvement usually starts after
identifying the most critical or vital areas.
Technique of using Pareto Analysis in combination with Cause-and-Effect (C-E)
diagram is very effective in solving problems. The most significant problem iden-
tified in the first Pareto chart becomes the effect in the C-E diagram. The causes
identified in the C-E diagram are subsequently prioritised in another Pareto chart.
This process is carried on until the vital few problems have been identified and
eliminated.
Thus, a Pareto diagram is an indispensable tool for problem analysis and con-
tinuous improvement activities. The general principles of construction for a
Pareto chart are not much different from a histogram. Any textbook on quality
management, quality circles, or descriptive statistics should contain the simple
steps to constructing a Pareto chart. Leaders and top management professionals
should have no qualms about practicing this powerful yet simple tool.
CAUSE-AND-EFFECT DIAGRAM (ISHIKAWA/FISHBONE DIAGRAM)
Cause-and-Effect (C-E) diagram utilizes judgmental techniques to identify and
evaluate the cause factors for any effect or output that have already happened or
it may have been otherwise planned. This effect or output could be a problem, a
task or a result, having either or both of tangible and intangible characteristics.
According to Dr Kaoru Ishikawa, who invented the C-E diagram, a ‘process’ that
is a collection of cause factors must be controlled to obtain better products and
effects. In other words the desired goal or characteristic is the effect of the inter-
action among or the impact of various cause factors, and therefore process stan-
dardization through control of cause factors can lead to a planned ‘effect’. Juran,
in his QC Handbook (1962), had honoured Ishikawa by naming the ‘cause-and-
effect diagram’ after him; today it is popularly known as the Ishikawa Diagram.
344 TOOLS, TECHNIQUES AND STRATEGIC ENABLERS
This tool is used as both ‘vanguard’ and ‘rear-guard’ control. The term ‘van-
guard’ control refers to anticipating problems and preventing them before they
actually occur. ‘Rear-guard’ control implies taking action after the occurrence. The
versatility and simplicity of the Ishikawa diagram makes the technique applicable
across diverse behavioural and operational fields, and not just in manufacturing;
it encompasses all processes relating to design, purchasing, sales, service, person-
nel, accounting, software, information technology, administration, etc. Ishikawa
further elaborates that since politics, government and education are all processes
whose characteristics are dependent on causes, controlling of these causes
through C-E diagrams will benefit the output or effect of all these processes as
well. The tool is particularly useful in a non-numerical situation, where a problem
or issue cannot be analysed by collecting and studying numerical data to start with.
The diagram is also called by the nickname Fishbone Diagram, owing to its
characteristic shape resembling to that of fish bones. Figure 11.1 shows the princi-
ples behind the C-E diagram that probes the interrelationship between causes and
sub-causes and effects or outputs. The ‘effect’ or the ‘problem’ is written on the
extreme right-hand-side of the diagram, which symbolises the spearhead of the
base (reference) line of the diagram. The major categories that could impact the
effect or problem are listed on either side of the base line and are connected to the
base line through a slanted or vertical line. The causes and sub causes, and maybe
other significant micro causes of each category are shown according to their inter-
relationship.
SEVEN QC TOOLS 345
Figure 11.1: Conceptual Framework of Cause and Effect Diagram
PROCESS
Cause Factors
Characteristics
Effect
Material
Men
Method
Machine
Measurement
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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