Root Cause Analysis – 5 Why’s & 5 How’s

Many people are familiar with the 5 why’s as a problem analysis tool to get at root cause. Originally conceptualized by Toyota and discussed by Taiichi Ohno in a 2006 article. The 5 Why’s are also used as part of the PDCA (Plan, Do, Check, Act) cycle.

While a company may look to implement a short term solution, an immediate corrective action, it is important for all companies to get to the root cause as a means to resolve the actual issue rather than continue to react to a symptom of the problem.

Here is an example:

Problem: There is oil under equipment

1st Why – Why is there oil under equipment?
Initial investigation showed that a hose why leaking.

2nd Why – Why is the hose leaking oil?
Further investigation showed that the hose was rubbing on a drive belt and the belt had worn through the hose.

3rd Why – Why was the hose rubbing on the belt?
The bracket that secured the hose had fallen off.

4th Why – Why had the bracket fallen off?
The bolts hold the bracket has loosened up and fallen out.

5th Why – Why had the bolts loosened up?
The equipment had not been serviced in the last 3 months. – This is clearly the root cause and allows a company to take specific action – a preventive action.

As Taiichi Ohno said “Data is, of course, important in manufacturing,” but he also often remarked, “but I place greatest emphasis on facts.”. Ultimately, it is the employees that are closest to the process that can provide insight during the root cause analysis. Management that is involved in root cause analysis need to go to source, engage employees and gather facts.

Companies can also use the 5 How’s as a means to get to the most effective solution. The 5 How’s, like the 5 Why’s, is an iterative process, looking deeper at each proposed solution as a means to make sure the solution implemented is a long term solution, effectively “error proofing” the process.

Here is an example based upon the above:

Step one is an immediate corrective action – replace the hose and bracket and make sure the bolts are properly torqued. Next how do we put in place a long term, preventive action, a solution?

1st How – How do we make sure the equipment is serviced regularly?
Develop and implement a preventive maintenance program.

2nd How – How do we ensure the preventive maintenance program is implemented?
Utilize scheduling tools and produce a weekly preventive maintenance job list.

3rd How – How do we ensure the preventive maintenance program is effective?
Create a preventive maintenance log and assign a supervisor or manager to verify that scheduled preventive maintenance occurs.

In our example, we have included (5) Why’s and (3) How’s. The number of Why’s or How’s is much less important than finding and fixing the root cause of the problem.

The time invested will yield long term savings and allow companies to focus on their core mission and better serve their customers. There is a wealth of information available online about root cause analysis and using the 5 Why’s and companies would be well served to train their staff at all levels to always look for the root cause.

Matt Service is President of PositiveROI and uses his 35+ years of experience with operations and process improvement, technology and regulatory compliance when working with companies to reduce costs, improve operations and increase customer satisfaction. Matt is available for consulting, as a fractional COO or part-time COO.