Fishbone Diagrams

The Fishbone Diagram is a problem analysis technique for which credit is usually given to Professor Kaoru Ishikawa, a specialist in quality control. It is sometimes called a Ishikawa Diagram.

The fishbone diagram is aimed at the analysis portion of the problem solving process. It helps to identify the areas where change or improvement might be desirable. Other techniques such as brainstorming can then be used to suggest what the actual changes might be.

Diagrams can be simply drawn of a flip chart or white-board for team work or alternatively you can buy special templates and software.

What Is A Fishbone Diagram?

The fishbone diagram is essentially a tree structure placed on its side with all the lines feeding into the main trunk or backbone. The name comes from the resemblance of the finished diagram to the skeleton of a fish!

The main problem or goal (I refuse to use the word "opportunity"!) is first represented as a large horizontal arrow. Elements that influence this are then drawn as backward sloping lines feeding into the main problem. Each line can itself have further lines feeding into it and so on.

Initially it will be easy to draw these "bones": for example if the problem is "increase sales" then we would obviously have lines for "product", "pricing", "placement", etc. Once the obvious lines have been drawn people will need to think harder to extend the diagram and it is here that breakthroughs might occur.

A fishbone diagram has an almost fractal nature: Each "bone" can itself be seen as a complete fishbone diagram, which is in turn comprised of still further diagrams. This allows important pieces of the problem to be identified and picked out for further analysis and team allocation. Be careful not to forget the interaction between different areas of the problem!

One of the great advantages of the fishbone diagram is its simplicity. It is a very easy technique to use and the results are visually intuitive. However this simplicity is also a disadvantage in that for many problems the forces at work interact in a complex manner and can't be broken down into a simple directed tree in this way. It's therefore important to remember that the diagram is an aid to and not a restriction on creativity.