Warm up Q

Why is a software little fix called patch ?

5 whys

Megatron / Retrospective / Sprint 23

Sakichi Toyoda

A little history

Toyota production system

"the basis of Toyota's scientific approach . . . by repeating why five times, the nature of the problem as well as its solution becomes clear."

What is 5 whys?

Technique is to determine the root cause of a defect or problem

Iterative question-asking technique used to explore the cause-and-effect relationships underlying a particular problem

Empirical observation

Example

The vehicle will not start. (the problem)Why? - The battery is dead. (first why)Why? - The alternator is not functioning. (second why)Why? - The alternator belt has broken. (third why)Why? - The alternator belt was well beyond its useful

service life and not replaced. (fourth why)Why? - The vehicle was not maintained according to

the recommended service schedule. (fifth why, a root cause)

people do not fail, processes do

the real root cause should point toward a process that is not working well or does not exist

classical answers : not enough time

not enough investments

not enough manpower

May be true -> but are out of our controlInstead of asking the question why?, ask why did the

process fail?

To notice

Simple and robustDrawbacks:

POVNot data drivenNot for complicated problems

Focus on facts

Example 2

My customer is unhappy (the problem):

Why? – I didn’t deliver the project on time. (first why)

Why? – The job took much longer than I thought it would. (second why)

Why? – I underestimated the complexity of the project. (third why)

Why? – I didn’t develop a proper plan and quickly made an estimate of the time required. (fourth why)

Why? – I was running behind on other projects and lacked the time to plan. (fifth why, a root cause)

Read more

http://en.wikipedia.org/wiki/5_Whys

Let’s practice it on an example we have