Some methods for conducting root cause analysis include the five whys, the fishbone diagram and the causal tree. All three methods provide a systematic process for determining the root cause of a problem or event.
When conducting a root cause analysis, the first step is to accurately define the problem and then gather information. The next step is to identify the issues and events that led up to the problem. One simple method to analyze the factors that contributed to a problem or event is the five whys technique. Starting from the problem, simply ask why it happened. If the answer requires further investigation, ask why again, and continue asking why and drilling down further until the root cause is determined.
The fishbone diagram builds on the five whys technique by separating the possible causes of an event into different categories, such as policy, procedures, environmental factors or other categories that may be relevant. Once the potential causes are identified, use the five whys technique to help determine the root causes.
In the causal tree method, the problem or event being investigated is placed at the top. Determine the direct causes for that event, and then determine the causes for those events, proceeding in a tree-like manner until the root causes are reached.