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Effective Usage of the Fishbone Diagram
By Tony Jacowski

The most popular tool to sort out problems is the Ishikawa Cause and Effect Diagram, which was first used in 1943 Kaoru Ishikawa to sort out certain work related issues. It is also popularly known as the Fishbone diagram.

It is a visual depiction of the relationship between the causes and effects of a problem and defects. Additionally, it helps to come to a consensus on the issues, so that the project moves ahead steadily in resolution of the problems. It is very useful in the Measure and Improve phases of Six Sigma.

A major benefit is that it involves an in-depth study of the various factors that affect the process.

How You Can Use It

With the help of a tool like the Pareto analysis, you may be able to pinpoint the problem that needs immediate attention. You put this problem area in a box, which depicts the head of the fish and draw a line for the backbone of the fish.

Once done, you need to draw a diagonal line from left to the center to depict the primary causes and alternate these ribs on either sides and label them. You can depict the secondary causes which affect the primary causes by depicting them as a medium-sized bone on the left and right of the rib.

You can go on in a similar way for the smaller or lower level secondary causes. Once done, you examine the diagram and you will find the most important causes. Mark them specifically for further action to be taken. To find the causes of the problem, you can brainstorm to create a list of all the causes.

It is typical to find man, machine, material, method and environment as the causes listed amongst the other factors. You may alternately list the steps of the process and understand the problems that arise in a step-by-step manner.

However, you may find a repetition of the causes in such a scenario.

Making the Diagrams Effective

It is necessary to get input from as many people as possible. This will make the diagram as accurate as possible. Additionally, those who participate will be informed about these factors.

If you make one Ishikawa Diagram for every CTQ that you have identified, it will become easier for you to understand the problems. If you combine all into one diagram itself, it will become highly complicated to understand.

It is necessary that you find concrete causes rather than the generalized ones. At the same time, break them down to the point that they are well understood for further action.

With the participation of all the fishbone helps to form a common understanding of the factors causing the problems. It can be the roadmap to undertaking the collection of required data for further purposes.

The fishbone diagram helps to understand processes that need changes and those that are required to be rejected.

Tony Jacowski is a quality analyst for The MBA Journal. Aveta Solutions – Six Sigma Online ( ) offers online six sigma training and certification classes for six sigma professionals such as, lean six sigma, black belts, green belts, and yellow belts.

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