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Chapter 18 Operations improvement 563
Why–why analysis
Why–why analysis
Why–why analysis starts by stating the problem and asking why that problem has occurred.
Once the reasons for the problem occurring have been identified, each of the reasons is taken
in turn and again the question is asked why those reasons have occurred, and so on. This
procedure is continued until either a cause seems sufficiently self-contained to be addressed
by itself or no more answers to the question ‘Why?’ can be generated.
Worked example
Kaston Pyral Services Ltd (E)
The major cause of unscheduled returns at KPS was the incorrect prediction of reasons
for the customer’s system failure. This is stated as the ‘problem’ in the why–why analysis
in Figure 18.12. The question is then asked, why was the failure wrongly predicted? Three
answers are proposed: first, that the engineers were not trained correctly; second, that
they had insufficient knowledge of the particular product installed in the customer’s
location; and third, that they had insufficient knowledge of the customer’s particular
system with its modifications. Each of these three reasons is taken in turn, and the questions
are asked, why is there a lack of training, why is there a lack of product knowledge,
and why is there a lack of customer knowledge? And so on.
Figure 18.12 Why–why analysis for ‘failure wrongly predicted’