The Cause & Effect, or Fishbone Diagram, was first used by Dr. Kaoru Ishikawa of the University of Tokyo in 1943 - hence its frequent reference as a "Ishikawa Diagram". This diagram is used to identify all of the contributing root causes likely to be causing a problem. This methodology can be used on any type of problem, and can be tailored by the user to fit the circumstances. Use of this tool has several benefits to process improvement teams: * Straightforward and easy to learn visual tool.
* Involves the workforce in problem resolution - preparation of the fishbone diagram provides an education to the whole team. * Organizes discussion to stay focused on the current issues. * Promotes "System Thinking" through visual linkages.
* Prioritizes further analysis and corrective actions.
How to Get Started
This tool is most effective when used in a team or group setting. 1. Use a white board, butcher-block paper, or a flip chart to get started. You may choose to use "Post-it" notes to move causes around as you decide on categories. 2. Write the problem to be solved (the EFFECT) as descriptively as possible on one side of the work space, then draw the "backbone of the fish", as shown below. The example we have chosen to illustrate is "Missed Free Throws" (an acquaintance of ours just lost an outdoor three-on-three basketball tournament due to missed free throws).
3. The next step is to decide how to categorize the causes. There are two basic methods: A) by function, or B) by process sequence. The most frequent approach is to categorize by function.
In manufacturing settings the categories are often: Machine, Method, Materials, Measurement, People, and Environment. In service settings, Machine and Method are often replaced by Policies (high level decision rules), and Procedures (specific tasks).