9akk105151d0113 5 whys

5 WhysBasic technique for finding root causes

ABB Basic Quality Tools Series

© ABB Group 9AKK105151D0113

15 July 2010, Slide 1

5 Why’s - ContentWhat is it for?

• A quick and simple tool for understanding the real root causes of a problem

• To push thinking about potential root causes to the root level.

Where could I use it?

How do I use it?

• In the Q2 Analyze phase of an improvement project to understand root causes.

• Where a quick tool is required for understanding cause and effect in the field.

• Can be used in conjunction with a Fishbone diagram to understand more “bones”.

Risks and how to avoid them

• Establish the problem – write it down

• Ask Why the problem is happening –write it down.

• Ask Why again (to the last answer) and write it down.

• Keep asking Why until the real root cause is identified.

• This may take more or less than 5 Whys

Example

Why?.Why?..Why? ...Why? ....Why?



Expected Benefits:

• By continually asking Why? The process encourages a more rigorous investigation of the real root cause. It avoids the temptation to stick with the first answer given.

Uses of this tool:

• As a simple tool that can be used at the problem location to challenge potential root causes .

• It can be used together with a Fishbone / Ishikawa diagram to establish more bones.

• It can be used in a team to thoroughly interrogate root causes.

5 Why’s - What is it for?



Background:

• Potential root causes require in depth interrogation. Often the initial root causes proposed are not the real root causes.

• The 5 Why’s technique pushes and tests the understanding of root causes and avoids superficial causes being accepted.

Uses:

• Use it to identify root causes for problems which are not clear and may have a deeper real cause.

• Use it during the analysis phase to gain a deeper understanding of root cause by pushing understanding of potential root causes.

5 Whys - Where could I use it?



5 Whys - How do I use it?

State the problemState the problem

Procedure and Guidance Notes:• Clarify the problem and write it down It is important that there is clear understanding

of the problem before 5 Whys is started.

Ask Why the problem happens


• Ask Why the problem happens (Why 1)• Write down the potential cause

It can be good practice to use in conjunction with a Fishbone diagram. Ask Why a each “bone.”



• For the potential cause or outcome identified, ask why it happens (Why 2)

• Write down this next potential root cause.

Keep asking WhyKeep asking Why

• For the next potential root cause or outcome, again ask why it happens (Why 3)

• Write down the new potential root cause• Repeat the process until the real root cause is identified.

There is no magical formula about 5 Whys’ Sometimes you may get to the root cause after two or three whys, sometimes you my have to ask more than five times.Stop when you have reached a root cause that the team agree and can act on.

Record Root Cause

Record Root Cause

• Record the actual root cause identified.



5 Whys - Risks and how to avoid them:Risks :• Not asking Why enough times can lead to a superficial

root cause.

Steps to avoid them :• Ensure that the process is repeated enough times until

the team is happy that a good potential root cause has been identified.



5 Whys - Example

Q : WHYWHY has machine stopped ?A : Overload tripped out

Q : WHYWHY overload trip ?A : Insufficient oil on shaft

Q : WHYWHY Insufficient oil ?A : Oil pump is inefficient

Q : WHYWHY is pump not efficient ?A : Pump drive shaft worn

Q : WHYWHY is the pump shaft worn ?A : Oil filter is blocked by metal scrap

1 2 3

4 5



Continue to ask Why does the previous outcome occur until you’ve reached potential root cause. Which you can record

Ask Why does the outcome (Why 1) occur? (why 2)

Consider the potential root cause of the problem ( can be done in conjunction

with a fishbone diagram)

5 Whys - Example

2. Identify potential root cause (Why 1)

3. Write down potential root cause

4. Identify potential root cause (Why 2)s

6. Record the root cause

Write down the problem being investigated

1. Define the problem

5. Write down potential root cause

Flashover during High Voltage Test on MV Transformer

1 Because the bushing socket was loose

2 Because the lock washer for the spring plate was not installed properly

3 Because the workman could not fit it in place and left it out – and did not tell anyone!

4 Because the spring plate was made too thick

5 Because the subcontractor made a mistake when transferring the dimensions from the drawing to the CNC program

6 Because XXABB sent drawings, not CAD files to subcontractors

Sustain Solution: Send CAD files instead of drawings. Change work procedure and meet with all sub-contractors affected by change



9akk105151d0113 5 whys

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