Building Your Cause and Effect Diagram

Once a high-level process has been mapped, the performance improvement team discusses the potential causes of defect within each process step. The Cause and Effect Diagram is a process tool that has traditionally been used to highlight potential causes. This diagram is the brainchild of Kaoru Ishikawa, who pioneered quality management processes in the Kawasaki shipyards and, in the process, became one of the founding fathers of modern management.

The Cause and Effect Diagram is also known as the fishbone diagram because it was drawn to resemble the skeleton of a fish, with the main causal categories drawn as "bones" attached to the spine of the fish.

Sample Project RED Cause and Effect Diagram

The Cause and Effect Diagram is used to explore all the potential or real causes (or inputs) that result in a single effect (or output). Causes are arranged according to their level of importance or detail, resulting in a depiction of relationships and hierarchy of events. This diagram can help you search for root causes, identify areas where there may be problems, and compare the relative importance of different causes. Causes in a Cause and Effect Diagram are frequently arranged into four major categories, and health care teams often use the categories of equipment, policies, procedures, and people.

To successfully build a Cause and Effect Diagram, the performance improvement team should:

• Be sure everyone agrees on the effect or problem statement before beginning.
• Consider possible causes for each “bone” in the fishbone.
• Pursue each line of causality back to its root cause.
• Consider grafting relatively empty bones onto others.
• Consider splitting up overcrowded bones.
• Consider which root causes are most likely to merit further investigation.

Discuss each variable on the fishbone that may positively or negatively impact patient readmission and then use this discussion to prioritize issues for further investigation and project scoping.

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