The Five Why’s

By: Romains Bos

• Introduction• The Five Why’s In Action• Why Five?• Test It! Does It Hold Up Backwards?• Summary• Foundations of Project Success

Agenda

• Root cause analysis is a fundamental aspect of continuous improvement

• It’s how we figure out the difference between defects and errors – errors cause defects

• There are many forms of root cause analysis:• Descriptive frameworks• Statistical packages• Investigative methods

• The Five Whys is a simple and proven method for reaching the same conclusions

Introduction

A two-week old washing machine suddenly stops working . . .

The Five Why’s In Action

Why did the machine stop working?

1st Why:

The fuse blew

Why did the fuse blow?

2nd Why:

The motor overheated

Why did the motor overheat?

3rd Why:

The shaft was misaligned

Θ

A two-week old washing machine suddenly stops working . . .

The Five Why’s In Action – Cont’d

Why was the shaft misaligned?

4th Why:

The shaft bearing was damaged

Why was the bearing damaged?

5th Why:

Θ

The shaft seal was missing

• Obviously, most causes of defects won’t be exactly five whys deep

• “Five” promotes persistence, rather than the assumption of simple cause and effect

• Don’t stop until you get to the root cause, but once you’ve reached the root cause, stop

Why Five?

Test It! Does It Hold Up Backwards?Shaft seal was missing

Did that cause…?

The shaft bearing to be damagedDid that cause…?

The shaft to be misalignedDid that cause…?

The motor to overheatDid that cause…?

The fuse to blowDid that cause…?

Event: Washing machine to suddenly stop working

• Root cause analysis is an important aspect of continuous improvement because it helps us to identify the errors that cause defects

• We use the five whys to ensure that we drill down to the root causes of problems

• “Five” promotes persistence; most root causes will not be exactly five levels deep

Summary

Foundations of Project Success

Scope and Requirements

Sch

ed

ul

eProject Success

Qualit

y

Cost

Integrity and Safety

The End

Questions?

Comments?