Root Cause Analysis (RCA) is an effective problem solving technique that helps an organisation identify the origin, or root cause, of a problem using specific sets of steps, and associated tools. The key objectives of this process are to:
- Determine what happened.
- Determine why it happened.
- Determine what to do to reduce the likelihood that it will happen again.
The associated tools of RCA include:
- 5 Why Analysis
- Fishbone (Ishikawa) Diagram
5 Why Analysis
5 Why analysis is a simple tool which identifies the root cause of a problem by repeatedly asking the question “Why”. It is commonly accepted that you can identify the root cause by asking “why” five times, although this is not a strict limit. The objective is to peel away the layers of symptoms leading to the true root cause of a problem. Figure 6 shows a simple 5 why analysis for a vehicle not being able to start:
Figure 6: 5 Why Analysis
The Fishbone (Ishikawa) Diagram
This technique was pioneered by Kaoru Ishikawa, a Japanese professor and quality management expert. An Ishikawa Diagram visualises a problem and explores the cause and effect relationship by categorising potential causes in order to identify multiple root causes. Importantly, as shown in Figure 7, Ishikawa identifies the factors which have a high or low impact on the problem so that multiple root causes can be prioritised.
Figure 7: A Route Cause Analysis Fishbone (Ishikawa) Diagram