Root Cause Analysis

When a problem occurs, it is important to get it fixed as quickly as possible.  Equipment not working will quickly affect your profits and your business reputation and senior management will want to minimise both of those.   But fixing a problem is only a piece of the problem and like an iceberg, there is a much bigger problem lurking behind the original problem; why did it happen in the first place?

If you have not eliminated the root cause of a problem, you cannot say with any certainty that it won’t happen again, and that is where root cause analysis becomes your friend.

On the face of it, root cause analysis sounds like an easy subject but, surprisingly, many people get it wrong and don’t go far enough with it to truly remove the actual mechanism of the failure and leave the possibility of it recurring in place.  Most people who are placed in charge of a root cause analysis will not go deep enough and what they finally identify as a root cause is actually one of the causal issues.  Sure, you can fix that, but you will still have the possibility of the problem happening again, and that is not only bad for business but potentially embarrassing for the person who declared that the problem was solved.

In most cases, if you think you have solved the problem, you probably haven’t, and you need to go back and re-examine it.

Root Cause Tools

Luckily, there are a number of well recognised business tools that have been developed to help uncover root cause events, and by using these, you stand a much better chance of successfully completing an analysis and truly uncovering the root cause of a problem.  Two of the most effective and widely used are:

5-Why’s. Simplicity itself, this type of analysis only requires the investigator to ask ‘why’ five times, but you might be surprised how difficult that actually is.  The idea behind it is that by continually asking why, you peel away the different levels of issue until you finally arrive at the true reason for the failure.  That is the problem that you must fix if you want the issue to be removed completely.  It sounds easy but rarely is; many people fail to drill down deep enough and stop at three why’s because they think that they have reached the cause, but that is unlikely after so few questions.  Five why’s should be based on the following format:

  • Write down the problem. Writing helps you to formalize the problem and describe it completely. If you work with a team, it also helps the team to focus on the same problem.
  • Ask yourself why did the problem happen and write down the answer.
  • Ask yourself – looking at your answer – again why did that issue happen and write down the answer.
  • And again, ask yourself – looking at your answer – why did that issue happen?
  • Ask yourself this question as often as necessary until the team agrees that the problem’s real root cause is identified.

For something so simple, Five-Why’s is a particularly effective means of getting to a root cause, provided that you are stringent with your use of it.

Ishikawa. Also known as the fishbone diagram, and even sometimes the Cause and Effect diagram, Ishikawa was developed in the Japanese manufacturing community, as were many other effective analysis tools.  This in particular is designed to highlight and understand the myriad issues that may contribute to a problem and help segregate the actual cause of the problem.  Based on a diagram format, Ishikawa has a central problem (the notional head of the fish shape) for which a number of possible causal categories fee into different elements associated with those categories are positioned to create a fishbone kind of structure.

The idea behind the diagram is to brainstorm the elements (or sub-inputs) behind the main inputs in an attempt to identify the weak areas and the actual area of failure. The actual inputs should reflect the type of problem and usually change based on the type of industry involved and can be changed in number.  Examples of this may include:

The 4 Ss’.  Generally used in service industries, inputs are:

  • Surroundings
  • Suppliers
  • Systems
  • Skills

The 8 Ps. Commonly used as a model for identifying crucial attributes for planning in product marketing, inputs are usually cited as:

  • Product (or service)
  • Price
  • Promotion
  • Place
  • Process
  • People (employees, and includes skills or availability)
  • Physical evidence
  • Performance

The 5 Ms. Cited as the original Ishikawa from the Toyota Production System, the 5 Ms system is one of the most common frameworks for root-cause analysis.

  • Machine (meaning equipment or technology)
  • Method (meaning process)
  • Material (to include raw material, consumables, and information)
  • Man / mind power (means physical work or knowledge)
  • Measurement / medium (includes inspection and work environment)

Modifying the Ishikawa to these and other specific criteria makes it a powerful tool which, if used properly can help identify weaknesses in systems or products.


Making it Work.

Root cause analysis is usually carried out in response to a problem that may be stopping production and that means that there is enormous time and management pressure to fix it, and that is when it is easy to accept something less than the true root cause as the solution. There are usually find three basic types of causes:

Physical causes – Tangible, material items failed in some way.

Human causes – People did something wrong or did not do something that was needed.

Organizational causes – A system, process, or policy that people use to make decisions or do their work is faulty.

The key to assessing a root cause is to examine every aspect of the problem and arrive at specific answers to each one.  Taking this in a series of steps:

  • One: Define the Problem. What do you see happening? What are the specific symptoms?
  • Two: Collect Data. What proof do you have that the problem exists? How long has the problem existed? What is its impact?
  • Three: Identify Possible Causal Factors. What sequence of events or conditions led to the problem?
  • Four: Identify the Root Cause. Why does the causal factor exist?
  • Five: Recommend and Implement Solutions.