The 5 Why Technique of problem
solving
For Want of a Nail
For want of a nail the shoe is lost;
For want of a shoe the horse is lost;
For want of a horse the rider is lost;
For want of a rider the battle is lost;
For want of a battle the kingdom is lost;
And all for the want of a horseshoe nail.
—George Herbert
Rationale
For every effect there is a cause. But the results chain between the two
is fairly long and becomes finer as one moves from inputs to activities, and then on to outputs and
outcomes.
In results-based management, the degree of control one enjoys decreases higher up the
chain and the challenge of monitoring and evaluating correspondingly increases.
In due course, when a problem appears, the temptation is strong to blame others or
external events. Yet, the root cause of problems often lies closer to home.
The Five Whys Technique
The technique of the 5 Whys was originally developed by Sakichi Toyoda
and was later used within Toyota Motor Corporation during the evolution of their manufacturing
methodologies.
When looking to solve a problem, it helps to begin at the end result, reflect on what
caused that problem by asking the simple question, "why". Why, or what caused (a) to happen.
Having established that (b) was the cause of (a) happening, we repeat the same
question, but directed at the (b) event.
But why the number five in the name? No real reason except that 5 is a 'nice' number
for a rule of thumb.In practice, we may have to pose the "why" question fewer or more times than the name
implies.
Criticisms
The 5 Why approach has been criticized by Teruyuki Minoura, former
managing director of global purchasing for Toyota, as being too basic a tool to analyze root causes to the depth
that is needed to ensure that the causes are fixed Reasons for this criticism include: ---
1) Tendency for investigators to stop at symptoms rather than going on to lower level
root causes.
2) Inability to go beyond the investigator's current knowledge - can't find causes
that they don't already know.
3) Lack of support to help the investigator to ask the right "why"
questions.
4) Results aren't repeatable - different people using 5 Whys come up with different
causes for the same problem.
5) Tendency to isolate a single root cause, whereas each question could elicit many
different root causes.
An example of the 5 why approach (1)
My car will not start. (the problem)
1) Why? - The battery is dead.
2) Why? - The alternator is not functioning.
3) Why? - The alternator belt has broken.
4) Why? - The alternator belt was well beyond its useful
service life and has never been replaced.
5) Why? - I have not been maintaining my car according to
the recommended service schedule.
6) Why? - Replacement parts are not available because of
the extreme age of my vehicle.
Outcome:- I will start maintaining my car according to the recommended service
schedule. (solution)
See also the
ISHIKAWA TECHNIQUE
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