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The Toolbox, Volume 2: The Fishbone Diagram

by Doug Paulin
Senior Manager, Logile, Inc.

Many individuals that find themselves managing labor programs do not have formal training in engineering concepts that are incredibly helpful to ensuring their success and the success of their company. The Toolbox looks to cover one of these concepts each month, providing useful instruction, templates, and tools that you can put into practice.

This month’s tool download: Fishbone Diagram and Analysis Frameworks

In this month’s installment of The Toolbox, we are going to look at a common problem that teams encounter while managing operations – we have a process that is producing an unintended or undesirable result, but we do not know what the cause is. Whether the process is a food program in a grocer, a customer engagement program in a retail environment, a fabrication step in a manufacturing process or a material handling operation in a distribution environment, unintended or undesirable results such as increased shrink through food waste, decreased customer satisfaction scores, excessive defects or increase pick times are all too common occurrences. If your organization has clearly defined standards and regularly reports on performance against these standards, you will at least be able to identify the problem quickly. However, where do you and your team start in terms of identifying the root cause?

There are a number of industrial engineering and statistical approaches that we can utilize to perform process improvement – Lean, Six Sigma, Business Process Reengineering – but in most examples a critical early step is brainstorming a number of causes that you and your team will need to identify in order to perform proper testing and analysis to identify the root cause or causes. Enter the Fishbone Diagram.

A Fishbone Diagram (also known as an Ishikawa diagram, named after Kaoru Ishikawa who is considered one of the founding fathers of modern management) is nothing more than a simple, structured approach to brainstorming cause and effect. Again, this is not the tool that will help you identify exactly what the cause of your unintended or undesired result – it is a starting point for you and your team that will simplify how you begin your improvement process. All too often, a team will meet to discuss the problem at hand and, depending on pre-conceived notions, bias opinions or individuals’ area of expertise, the discussion will turn into a debate at the conclusion of which there is no clear direction or consensus on what the next steps will be.

Using a Fishbone Diagram, we can introduce a uniform process in which everyone knows they will get a turn to list a potential cause. The output of this tool and exercise is merely to list out and categorize all the potential causes. The diagram gets its name from the shape of the drawing. You first list the unintended or undesirable result to the right of the page in a box (the “head”), drawing a long line from the box across the page (the “backbone”). You then draw lines off the “backbone” listing categories of problems that may contribute to the result (the “bones”). Finally, you brainstorm and list potential causes on each “bone” that the team may want to explore.

Fishbone Diagram

Figure 1 – An example of a Fishbone Diagram examining the potential causes of a specific product’s low profitability, utilizing The 4 P’s framework on the bones to categorize potential causes

So, now that we understand how to draw our Fishbone Diagram, how do we structure our brainstorming session so that we can easily and simply categorize the potential causes, or, what goes on the bones? It most likely depends on the unintended or undesirable result that you and your team are trying to solve for. There are numerous questioning or problem-solving frameworks that you and your team can use to structure your critical thinking process. In Figure 1, we used The 4 P’s – Product, Price, Placement and Promotion – to categorize our potential causes.

Using a framework should both help the team stay on topic, but also think of potential causes that they may or may not have influence over. Depending on the type of unintended or undesirable result that is being solved for, one framework may be better than the others. Popular frameworks include Porters’s 5 Forces, The 4 C’s and The 4 P’s, but there are numerous potential examples. You and your team can even use generic categories that you feel are relevant to your business. The tool provided in this installment (download link provided at the top of this post), includes both a template to create your own Fishbone Diagrams as well as a list of references for available frameworks and when they are most appropriate.

Again, the Fishbone Diagram is just a visual root-cause analysis tool, but it is one that allows you and your team to conduct a focused approach to brainstorming causes for an unwanted problem. Challenge your team to identify all potential root causes. There is a tendency to focus only on those within your collective control. The root cause of your unwanted problem may very well be outside of the control of those involved in the exercise. In facilitating the use of the Fishbone Diagram brainstorming session, it works well for the leader to fill in the categories ahead of time to ensure you include a representative who can speak to each category.

Remember, completion of the diagram is only one step, and a very preliminary one at that, in solving the problem. Depending on the process that you are using, whether it be Six Sigma’s DMAIC process – Define, Measure, Analyze (the step you would use the Fishbone Diagram), Improve, Control – or other process improvement strategies, the Fishbone Diagram will certainly be a great tool in your toolbox, especially to get the wheels turning on the path to identifying potential root causes and designing tests to address your problems and improve your results.


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