The 5 Whys analysis is a troubleshooting technique that allows you to get to the root of a problem fairly quickly. It became popular as part of the Toyota production system (1970s). Applying the strategy involves taking any problem and asking “Why? What caused this problem?”

By repeatedly asking the “Why” question (five is a good rule of thumb), it is possible to remove layers of symptoms to identify the root cause of a problem. Very often, the first reason for a problem will lead you to another question and then to another. Although this technique is called the “5 why”, you may have to ask the question fewer or more than five times before you find the problem related to a problem.

An example of a five why analysis … The “wheel” example.

Why is our biggest customer dissatisfied?

– Because our bike deliveries have been late for the last month.

Why have our bike deliveries been late for the last month?

– Because production has been delayed.

Why has production been delayed?

– Because there is a shortage of wheels.

Why do we have a shortage of wheels?

– Because the incoming inspection has rejected a large number of wheels for not being round.

Why do we reject so many parts?

– Because the purchase was switched to a cheaper wheel supplier that has inconsistent quality.

Benefits of the 5 whys:

– Helps to quickly identify the root cause of a problem.

– Helps determine the relationship between the different root causes of a problem.

– It can be learned quickly and does not require statistical analysis to use.