The Ishikawa Diagram; Fish-Bone Diagram; Cause-and-Effect Diagram

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The Ishikawa Diagram (Page 2 of 2)

The Ishikawa Diagram is usually constructed by the problem-solving team using the following basic steps:

1) prepare the basic framework of the Ishikawa Diagram on a large writing area, such as a whiteboard or a flipchart;

2) define the problem that needs to be addressed and describe it in clear and specific terms, then write this description in the problem box or fish head of the diagram;

3) finalize the cause categories of the major branches and write these at the tips of the major branches; if the members are all new to the Ishikawa Diagram and can't decide on which categories to write, use the 4 M's as categories;

4) conduct the brainstorming session using these basic brainstorming guidelines:

a) each participant will be asked one at a time to give a cause of the problem (only one input per turn!), saying 'Pass' if he or she can't think of any during his or her turn;

b) each cause identified will be 'hung' on the major branch of the category it belongs to; if it's the cause of another cause that's already on the diagram, then it must be 'hung' on the branch of the latter; if applicable, a cause may be placed on several branches;

c) the brainstorming session will continue until everyone says 'Pass'.

5) interpret the Ishikawa Diagram once it's finished.

There are many ways to interpret the Ishikawa Diagram. The fastest and simplest way to do it is for the group to choose the top five causes on the diagram and rank them, using their collective knowledge and any data available. The selection of the major causes may be done by voting or any other process that allows the group to agree on the ranking. The selected causes are then encircled on the diagram, with their ranks written beside them. The team may then investigate these causes further and use problem-solving techniques to eliminate their occurrences.

Figure 2. Example of a simple but finished Ishikawa Diagram

See Also: Pareto Chart; Brainstorming

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