As the name implies when using this technique, 5 Whys, one asks iteratively 5 times Why.
This technique relies by and large on the assumption that a given problem has a Root Cause. Once we have identified that root cause we can do something about it, i.e. remove it. In doing so the Problem is considered to be solved.
5 Whys was originally developed by Sakichi Toyoda and was used within the Toyota Motor Corporation. Sakichi Toyoda was a Japanese inventor and industrialist. He was the son of a farmer and sought-after carpenter, he started the Toyoda family companies. Toyoda is referred to as the "King of Japanese Inventors".
Basically with the 5Whys technique we iterate asking Why until we have identified a cause or set of causes which once are taking care of / removed solves the problem under consideration.
So we would start with a problem definition and then keep asking Why at each answer to uncover what is supposed to be the root cause.
Take a previous problem statement and ask:
Why is the problem Happening / Happened?
What caused the Problem to happen?
Why does this problem exist?
Why did this problem Originated / Started in the first place?
Once we ask the one of the above questions we'll get a Because Answer. To the Because Answer we apply again the Why question. We repeat this 5 times. Keep in mind that 5 is relative number, based on the overall observations that one needs five iterations to solve a problem.
In practical usage we could have less or more than 5 iterations depending on the problem we are working on.
Basically we do the iteration until we have identified a cause (set of causes) which once are taking care of / removed solves the problem under consideration.
Problem Statement: The Computer doesn't work anymore.
1. Why the computer doesn't work?
– Because it doesn't get electricity.
2. Why doesn't it get electricity?
– Because we haven't payed the bill.
3. Why didn't we payed the electricity bill?
– Because we were gone for the summer holidays to France.
4. Why were we gone for the summer holidays?
– Because we were bored of USA.
5. Why were we bored of USA?
– Because we have visited all the places we wanted to see.
As you have probably realized this in the above example the last answer doesn't gets us closer to a practical solution for our problem statement.
So next time when you do the 5 Whys you should pay attention to:
- Discriminate causes from symptoms. Go beyond 5 iteration if root cause has not been identified.
- Make sure that the logic of cause-and-effect relationship makes sense.
- Reverse your answers using "and therefore" to test your logic.
- Avoid to jump to conclusions. Look for the cause step by step.
- Use facts and knowledge when answering.
- Emphasize the process, not people and avoid to leave "human error", "worker's inattention", "blame others", etc. as the root cause.
- Ask the question "Why?" until the root cause is determined, i.e. the cause the elimination of which will prevent the error from occurring again.
5 Whys Example:
Problem statement: The car will not start.
Why? – Because the battery is dead.
Why? – Because the alternator is not functioning.
Why? – Because the alternator belt has broken.
Why? – Because the alternator belt was worn out.
Why? – Because the car was not maintained (the root cause).
The Therefore (Backwards) Test for the 5 WHYs
After using the 5 Whys test yourself to check the validity of the answers. It may help you to make sure your logical chain is correct and helps to put counter measures in place to ensure that the problem won't happen again in the future.
The car was not maintained.
Therefore the alternator belt wore out.
Therefore the alternator belt broke.
Therefore the alternator was not functioning.
Therefore the battery was dead.
Therefore the car did not start.
Please also keep in mind that:
- five whys technique is a useful tool for engineers or technically based problems. In other areas might not work so well;
- the answer you came up are restricted to your current knowledge. Other persons with different backgrounds looking at the same problem will provide different solutions. Therefore Results are not repeatable;
-most people have a tendency to isolate a single root cause, whereas each question could elicit many different root causes.
