What is the ‘Five Why’ analysis and why use it?
The Five Why analysis traces its origin to Sakichi Toyoda of the Toyota Industries Co. It gained its reputation as a root cause technique thanks to lean manufacturing pioneer Taiichi Ohno of the related Toyota Production System (TPS). The belief was that, by diving deep into the issue, the investigator would gain more clarity into what was truly causing the problem.
Today, the Five Why analysis is a widely recognized problem-solving technique used in RCA investigations to narrow down the cause of a failure by asking ‘why did this occur?’ multiple times. By asking ‘why’ after each response, a new layer is uncovered until the true root cause of the problem is exposed and can then be rectified.
Using the Five Why analysis is effective because it understands that below the obvious symptoms of a problem there is a great catalyst. That problem can come in many forms: whether from inadequate maintenance, poor planning/scheduling, incomplete or malfunctioning sensor data, or an internal procedure that needs to be reassessed.
When using the Five Why analysis, the responses gathered through the causal pathway allow organizations to deploy long-lasting improvements that can avoid similar issues in the future.
The Five Why analysis as an RCA tool
As an RCA technique, the Five Why analysis helps to investigate an incident and diagnose the root of an issue without having to do an extensive root cause analysis. It is used proactively for investigations like near-miss incidents and non-critical equipment failures.
(Read more about RCA in our eBook ‘Four Steps to Improve Your Root Cause Analysis Program’)
The technique can be used by following these simple steps:
#1 Define the problem clearly and simply
Build a knowledgeable team with members who are involved with the specific project or equipment you are investigating. Use this team to agree on a clearly defined problem statement to get closer to the root of the issue. It is critical to agree on the definition of the problem and to focus on errors and inefficiencies within the processes.
#2 Clarify the Evidence
Outline the specifics of the problem and collect evidence from the incident. Evidence is information that is both valid and quantitative. Examples would be data logs, witness statements, instruments, physical symptoms, and observations.
Note: Do not stop at human error as this is usually the symptom of larger problems within the organization.
#3 Conduct the Five Why analysis
Once the evidence is outlined, ask the question ‘What could have caused this issue to occur?’ and record the answer with tangible evidence. An effective way to gauge whether you are focusing on the right problem is to ask whether the problem will occur again if the most recent answer to the problem is corrected or if anything else can produce the same problem. Continue with this causal pathway until you get to the root of the problem – typically this is a gap in processes within the organization.
Note: Not every case will reach the root cause at the fifth “Why” because a problem may require going deeper into the causal pathway. It is appropriate to continue until the root cause is identified.
#4 Design the right solutions for lasting process improvements
Once you reach the root cause of the issue, you can begin to design solutions that will remedy the issue.
A solution is considered appropriate if it:
- directly addresses the issue
- drevents a reoccurrence of the issue
- is controllable
- helps achieve organizational goals and objects
- does not create a ripple of more problems
With the solution in place, a detailed implementation timeline can be made with clear roles and responsibilities. This clarification ensures lasting improvements to the process with significant risk reduction.