Abstract

When a system does not perform to expectations, it is important to find out the cause and correct the problem. Identifying and fixing immediate causes may provide only a short-term solution. A permanent fix requires identifying and preventing the root cause. Root cause analysis is a questioning process that employs three tools. First, the process diagram is a visual display of the process; it traces actions to their roots. Second, barrier analysis identifies barriers that should buffer a target from problems. Examples of barriers include physical devices, special procedures, and quality assurance activities. Third, change analysis is the identification of what has changed in a system to cause it to misperform. The root cause analyzer uses these tools to ask questions about five systemic factors: personnel, procedures, equipment, raw materials, and the environment. Eventually the question-asking process becomes so well focused that it employs questions that usually are too embarrassing to ask. But root cause analysis needs tough questions.