A factor in a problem-fault-sequence is considered a root cause if removing it prevents the final undesirable outcome from recurring. A causal factor, conversely, is one that affects an event’s outcome, but is not the root cause. Although removing a causal factor can benefit an outcome, it does not prevent its recurrence with certainty.
Root Cause Analysis (RCA) is a popular and often-used technique that helps people answer the question of why the problem occurred in the first place. It seeks to identify the origin of a problem using a specific set of steps, with associated tools, to find the primary cause of the problem, so that you can:
- Determine what happened.
- Determine why it happened.
- Figure out what to do to reduce the likelihood that it will happen again.
RCA assumes that systems and events are interrelated. An action in one area triggers an action in another, and another, and so on. By tracing back these actions, you can discover where the problem started and how it grew into the symptom you’re now facing.
You’ll usually find three basic types of causes:
- Physical causes – Tangible, material items failed in some way (for example, a car’s brakes stopped working).
- Human causes – People did something wrong, or did not do something that was needed. Human causes typically lead to physical causes (for example, no one filled the brake fluid, which led to the brakes failing).
- Organisational causes – A system, process, or policy that people use to make decisions or do their work is faulty (for example, no one person was responsible for vehicle maintenance, and everyone assumed someone else had filled the brake fluid).
RCA looks at all three types of causes. It involves investigating the patterns of negative effects, finding hidden flaws in the system, and discovering specific actions that contributed to the problem. This often means that RCA reveals more than one root cause.
Step One: Define the Problem
- What do you see happening?
- What are the specific symptoms?
Step Two: Collect Data
- What proof do you have that the problem exists?
- How long has the problem existed?
- What is the impact of the problem?
You need to analyze a situation fully before you can move on to look at factors that contributed to the problem. To maximize the effectiveness of your RCA, get together everyone – experts and front line staff – who understands the situation. People who are most familiar with the problem can help lead you to a better understanding of the issues.
Step Three: Identify Possible Causal Factors
- What sequence of events leads to the problem?
- What conditions allow the problem to occur?
- What other problems surround the occurrence of the central problem?
During this stage, identify as many causal factors as possible. Too often, people identify one or two factors and then stop, but that’s not sufficient. With RCA, you don’t want to simply treat the most obvious causes – you want to dig deeper.
Step Four: Identify the Root Cause(s)
- Why does the causal factor exist?
- What is the real reason the problem occurred?
Use the same tools you used to identify the causal factors (in Step Three) to look at the roots of each factor. These tools are designed to encourage you to dig deeper at each level of cause and effect.
Step Five: Recommend and Implement Solutions
- What can you do to prevent the problem from happening again?
- How will the solution be implemented?
- Who will be responsible for it?
- What are the risks of implementing the solution?
Analyse your cause-and-effect process, and identify the changes needed for various systems. It’s also important that you plan ahead to predict the effects of your solution. This way, you can spot potential failures before they happen.