The Fishbone Investigation Method, also called the Ishikawa Diagram or Cause-and-Effect Diagram, is a problem-solving tool used to identify, analyze, and visualize the possible root causes of a problem or incident, especially in safety, quality control, and process improvement. Why It’s Called “Fishbone” It’s named “fishbone” because the diagram looks like a fish skeleton: - The head represents the problem or effect. - The spine represents the main path of analysis. - The bones (branches) represent the categories of possible causes. Purpose and Usage The Fishbone method helps teams: 1. Identify all possible causes of a problem, not just the obvious ones. 2. Encourage team discussion and systematic thinking. 3. Find the root cause, not just treat symptoms. 4. Support corrective action plans after incidents or quality issues. It’s widely used in: - Incident and accident investigations (Safety Engineering). - Quality control and Six Sigma. - Process improvement and audits. - Root cause analysis (RCA). How to Use the Fishbone Method Step 1: Define the Problem Write the exact problem statement at the “head” of the fish (e.g., “Frequent hand injuries during scaffolding work.”) Step 2: Identify Main Cause Categories Commonly used categories (6M model): 1. Man (People) human error, training, communication, etc. 2. Machine (Equipment) malfunction, poor maintenance, etc. 3. Method (Process) unsafe procedures, lack of SOPs, etc. 4. Material poor quality, wrong type, expired, etc. 5. Measurement inaccurate data, lack of monitoring, etc. 6. Mother Nature (Environment) temperature, lighting, weather, etc. Sometimes for service or safety industries, categories are customized. Step 3: Brainstorm Possible Causes Under each category, list every possible contributing factor. Step 4: Analyze and Identify Root Causes Evaluate each branch and ask “Why?” repeatedly (the 5 Whys technique) to trace back to the root cause. Step 5: Develop Corrective Actions Once the true cause is identified, plan effective corrective and preventive actions (CAPA). Benefits - Clarifies complex problems. - Promotes team collaboration. - Visually organizes causes for better understanding. - Prevents recurrence by addressing the true root cause. Copied