Fish Bone
Introduction
This is one powerful, visual, problem-analysis tool that can be used by anyone, anywhere, anytime. Often called the fish-bone or Ishikawa diagram, this simple diagram makes it easy to see just how a certain effect resulted from many root causes – hence the name ‘Cause and Effect (C-E) diagram.’ Its use focuses everyone’s attention in a structured way on the real root causes of a problem and avoids getting sidetracked onto symptoms.

Visible tools are powerful tools since 83% of what we know has come from a visual source. The ‘Fishbone’ enable everyone to bring their piece of knowledge … and leave with the whole. Mere words can never achieve this.

No one ever has all the pieces of a given problem or solution. The real power of this simple tool enables everyone to contribute their piece while seeing how it relates to those contributed by others. Its impact as a communication tool generates much animated discussion and new understanding.

Most problems are caused by recurring families of causes. In manufacturing, the families may include the 5Ms consisting of Manpower (people/staff), Materials, Methods (processes), Machines (equipment), and Measurement. In the service industry you may hear about the 5Ps – People (staff/employees), Provisions (supplies), Procedures (processes), Place (environment), and Patrons (customers/patients). Another is the 4 Ws of What, Why, When, Where.

Example
How to use it?
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"

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). In this case, we will use the manufacturing functions as a starting point, less Measurement because there was no variability experienced from measurements. You can also use process steps as bone for brainstorming.

4) You can see that this is not enough detail to identify specific root causes. There are usually many contributors to a problem, so an effective Fishbone Diagram will have many potential causes listed in categories and sub-categories.

5) The usefulness of a Fishbone Diagram is dependent upon the level of development - moving past symptoms to the true root cause, and quantifying the relationship between the Primary Root Causes and the Effect. You can take the analysis to a deeper level by using Regression Analysis to quantify correlation, and Designed Experiments to quantify causation.

6) After creating your chart on a flip-chart or white board, you can replicate it using most processing programs or spreadsheets (Microsoft Excel,Minitab).

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