Figure D. I Sample of starting an Ishikawa Diagram

The main goal is represented by the spine or trunk of the diagram and primary factors are represented as branches. Secondary factors are then added as stems, and so on. Creating the diagram stimulates discussion and often leads to increased understanding of a complex problem. These diagrams are extensively used in identifying solutions to systemic problems, such as identifying the cause of productivity loss on assembly lines, or lower customer satisfaction levels in a service organization.

The basic technique of developing these diagrams, together with a very simple example, is shown here. A problem-solving team will use the Ishikawa Diagram as follows:

1. Prepare a blank diagram in a format that can be viewed by the entire group. This could be a flipchart, board, projected through a data projector from a PC, etc.
2. Define the problem that the group is trying to solve in clear and specific terms and write it in the box at the 'fish head' box of the diagram.
3. Write the cause categories into the tips of the 'fish bones'. These should be fairly broad categories as the exact causes are not yet known. An example is shown in Figure D.1 in which the group is trying to find the cause for unacceptable levels of network downtime.
4. Use brainstorming techniques to get participants to suggest possible causes, and note these on the relevant branch of the diagram. A simple diagram has been completed in Figure D.2.
5. Interpret the diagram. This could be done by ranking the top causes based on experience and available data. Once the top causes have been selected, each one will be investigated further according to its rank and priority

Figure D.2 Sample of a completed Ishikawa Diagram

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