This document provides an overview of the 5 Whys technique for root cause analysis. The 5 Whys involves iteratively asking "Why?" to get to the root cause of a problem. It is done by taking an effect and tracing it back through layers of "whys" to reveal the underlying cause. An example is provided where a vehicle breaking down leads through 5 whys to discovering the root cause was increased fuel prices. Benefits are that it avoids assumptions and traces causality directly. Last answers should point to a process rather than factors like time or resources. Fishbone diagrams or a tabular form can be used to map the 5 Whys analysis.

1. Prepared by: Sambhujyoti Das,
Quality Assurance
5 WHY

2. Asking “Why?” may be a favourite
technique of your three year old child in
driving you crazy, but it could lead to the
root cause of a headache (The problem).
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3. Principle:
• 5 Whys is an iterative question-
asking technique;
• Explore the cause-and-effect relationships
underlying a particular problem;
• logical flow as one digs deeper into finding
the root cause(s);
The answer to each question then forms the
basis of the next question.
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4. An example:……(1)
You are on your way to attained a marriage
party of your dear ones and your wheeler stops
in the middle of the road.
•1. Why did your vehicle stop?
– Because it ran out of patrol.
•2. Why did it run out of patrol?
– Because I didn’t buy any patrol on my way to
work.
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5. An example:………(1) continued
• 3. Why didn’t you buy any patrol this
morning?
– Because I didn’t have any money.
• 4. Why didn’t you have any money?
– Because its month end and I exhausted my
salary.
• 5. Why did you exhausted my salary?
– Because the patrol price has increased 3rd
time within a month.
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6. An example:……(2)
Different product mono-cartons in a clinic
carton (Packaging Mixup). (the problem).
1.Why ? Clinic carton of different product.
(first why);
2.Why ? Carton mixup during packaging.
(second why);
3.Why ? Incorrect product details on clinic
carton. (third why);
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7. An example:……(2) continued
4. Why ? Misprinting from supplier. (fourth
why);
5. Why ? Line-clearance procedure was not
followed during plate cutting. (fifth why, a
root cause).
Fifth why suggests a broken process or an
alterable behaviour.
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8. Thumb rule:
• Five iterations of asking why is generally
sufficient to get to a root.
• The questioning for this example could be
taken further to a sixth, seventh, or higher
level.
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9. Benefits:
• Encourage the trouble-shooter to avoid
assumptions and logic traps.
• Trace the chain of causality in direct
increments.
• From the effect through any layers of
abstraction to a root cause that still has some
connection to the original problem.
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10. Mind it:
• Last answer points to a process.
• Untrained facilitators will often observe that
answers seem to point towards classical
answers such as not enough time, not
enough investments, or not enough
manpower.
• These answers may be true, but they are out
of our control.
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11. Techniques:
There are two primary techniques used to
perform 5 Whys:
•Fishbone (Ishikawa) and
•Tabular Form.
Fishbone diagram may be helpful to identify the exact
answer of each question.
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12. Tabular From - Worksheet:
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