Which quality improvement tool is used for root cause analysis?

• A. Fishbone diagram
• B. Flowchart
• C. Run chart
• D. Control chart

Answer: (A)

Root cause analysis aims to uncover underlying factors that drive a problem, not just the surface symptoms. The fishbone diagram, also known as an Ishikawa diagram, is designed for this purpose. It starts with the problem at the head of the fish and branches into major categories (commonly People, Process, Equipment, Materials, Environment, Methods, and sometimes Management or Measurement). This structure helps a team brainstorm and visually connect a range of contributing factors, making it easier to see how different causes relate and where to target investigations and interventions.

For example, if a medication error occurs, the diagram helps you group potential contributors into categories such as People (look-alike packaging, distractions), Process (double-check steps missing), Equipment (barcode scanning not functioning), Materials (look-alike pills), and Environment (busy ward). After mapping, you test the most plausible root causes with data and implement targeted changes, then monitor outcomes to ensure improvement.

In contrast, a flowchart shows the sequence of steps in a process, which helps you understand how a problem arises but doesn’t inherently identify root causes. A run chart tracks data over time to reveal trends or shifts, useful for seeing if an improvement sticks but not for pinpointing causes. A control chart adds statistical limits to distinguish normal process variation from special causes, focusing on process stability rather than mapping underlying reasons.