The cause-and-effect diagram was initially developed by Japanese quality expert Professor Kaoru Ishikawa. In fact, these diagrams are often called Ishikawa diagrams; they are also called fishbone charts for reasons that will become obvious when we look at an example. Cause-and-effect diagrams are usually constructed by a quality team. For example, the team might consist of service designers, production workers, inspectors, supervisors, quality engineers, managers, sales representatives, and maintenance personnel. The team will set up the cause-and-effect diagram during a brainstorming session. After the problem (effect) is clearly stated, the team attempts to identify as many potential causes (sources of process variation) as possible. None of the potential causes suggested by team members should be criticized or rejected. The goal is to identify as many potential causes as possible. No attempt is made to actually develop solutions to the problem at this point. After beginning to brainstorm potential causes, it may be useful to observe the process in operation for a period of time before finishing the diagram. It is helpful to focus on finding sources of process variation rather than discussing reasons why these causes cannot be eliminated.
Cause effect diagram is used to assist teams in categorizing the many potential causes of problems or issues that may exist in Business or even in day to day life, in an orderly way and in identifying root causes. As problems come in many shapes and sizes, fishes also come in such an amazing variety of shapes and sizes that there is no ‘typical’ fish skeleton, so the Fishbone can be of any shape and size. The causes identified by the team are organized into a cause-and-effect diagram as follows: 1. After clearly stating the problem, write it in an effect box at the far right of the diagram. Draw a horizontal (center) line connected to the effect box 2. Identify major potential cause categories. Write