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Saturday, January 22, 2011

5 Whys Analysis

5 Whys Analysis is a problem solving technique that allows you to get at the root cause of a problem fairly quickly.

It was made popular as part of the Toyota Production System (1970's). Application of the strategy involves taking any problem and asking "Why - what caused this problem?"

By repeatedly asking the question "Why" (five is a good rule), it is possible to peel away the layers of symptoms to identify the root cause of a problem. Very often the first reason for a problem will lead you to another question and then to another. Although this technique is called "5 Whys," you may find that you will need to ask the question fewer or more times than five before you find the issue related to a problem.

An example of a five Why Analysis . . . The "wheel" example.

Why is our largest customer unhappy?
- Because our deliveries of bicycles have been late for the last month.

Why have our bicycle deliveries been late for the last month?
- Because production has been behind schedule.

Why has production been behind schedule?
- Because there is a shortage of wheels.

Why are we having a shortage of wheels?
- Because incoming inspection has rejected a large number of wheels for not being round.

Why are we rejecting so many parts?
- Because purchasing switched to a cheaper wheel supplier that has inconsistent quality.

Benefits of the 5 Whys:
- It helps to quickly identify the root cause of a problem
- It helps determine the relationship between different root causes of a problem
- It can be learned quickly and doesn't require statistical analysis to be used.


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