What Is a Fishbone Diagram?

Key takeaways

• A fishbone diagram is a visual tool that you can use to help brainstorm and categorize the root causes of a problem.

• Fishbone diagram template structures vary; for example, the 4S fishbone diagram divides potential causes into four sections, while the 8P fishbone diagram has eight cause sections.

• A common fishbone diagram example is the simple fishbone diagram, which has no predetermined categories and lets you decide how many cause sections to include.

A fishbone diagram is an effective tool for conducting root cause analysis. Discover more about fishbone diagrams and how you can make one. If you’re ready to get your start in project management, earn the Google Project Management Professional Certificate, where you will have the opportunity to develop in-demand skills in areas such as quality assurance, change management, stakeholder communications, Agile software development, and more.

What is a fishbone diagram?

A fishbone diagram, also known as a cause-and-effect diagram, is a visual tool used to brainstorm and categorize potential root causes of a problem. By laying out these causes on a fishbone-shaped structure, teams can effectively identify the most likely reasons behind an issue and implement solutions.

When to use an Ishikawa fishbone diagram

When used effectively, a fishbone diagram serves as an easy-to-interpret schema for root cause analysis. Other benefits of using a fishbone diagram include:

• Easy identification of bottlenecks: With a fishbone diagram, you can visually map out interdependencies within your business process, making it easier to spot bottlenecks. When paired with data analysis tools, fishbone diagrams can help you gain deeper insights into operational inefficiencies.

• Address and eliminate recurring issues: Identifying the root cause of a problem allows you to address it at its source, minimizing the likelihood of similar bottlenecks recurring in the future. This, in turn, promotes sustained stability and efficiency in your business operations.

• Clear visualization of shifts in business strategy: Applying a fishbone diagram through multiple iterations of a change allows you to visualize and understand the broader implications of that change on interconnected processes. The iterative approach facilitates strategic adjustments to your business plan.

• Increased collaboration among teams: Fishbone diagrams promote synergy among team members by offering a medium for brainstorming solutions. The collaborative approach ensures that everyone contributes their insights and perspectives, leading to a more comprehensive understanding of underlying business issues.

What is the main purpose of a fishbone diagram?

The main purpose of a fishbone diagram is to identify and organize the possible reasons something is going wrong. It provides a framework for looking beyond symptoms and into the key factors driving the problem. The visual layout tends to make it easier to notice patterns and figure out where to focus your efforts.

How to make a fishbone diagram

To create a fishbone diagram, organize the possible causes on the left side, categorized by cause. These make up the "bones" of the fish. On the right side, place the effect or problem you are investigating, as the "head." This structure provides a quick way to visualize the various causes associated with the effect. Follow these steps to create your own fishbone diagram from the ground up:

1. Provide a problem statement.

A problem statement is the effect or problem you are investigating. It goes in a box with an arrow pointing to it on the right side of a flipchart page, as if forming the head of the fish. Everyone on the team agrees on the definition of the problem.

2. Define major cause categories.

Form the skeleton of your fishbone diagram with the major cause categories, which you connect to the backbone. To find these categories, have a brainstorming session with your team. The number of categories you create will vary according to your industry and the problem you’re solving. As an example, if you work in manufacturing, your major cause categories may be staff/people, equipment and machinery, processes and procedures, materials, environmental factors, and measuring procedures.

3. Brainstorm causes.

Now that you have your major cause categories in place, take time to brainstorm possible causes. You can use the categories as a way of generating ideas, or just list as many causes as you can think of, as a team.

4. Categorize causes.

Go through your list of causes and add them to the appropriate category on your diagram. These causes become the ribs on your diagram, joining categories to the backbone.

5. Discover sub-causes.

For each cause you identify, go deeper by asking effective questions, such as, “Why does this happen?” This causes layers of branches or “bones” on the diagram.

6. Identify root causes.

The final step is to identify the root causes of the effect or problem in the problem statement. To do this, look at the causes that appear most often and across more than one category.

4 common types of fishbone diagrams

Fishbone diagrams come in various types, each designed to address a specific challenge. Here are some of the commonly used fishbone diagrams:

1. Simple fishbone diagram

The most frequently used fishbone diagram, the simple fishbone, lets you define and create cause categories unique to your organization or industry. With no predetermined category of causes, the simple fishbone diagram is the most versatile. For instance, when analyzing negative customer feedback, you might categorize causes as product-related and service-related concerns.

2. 4S fishbone diagram

The 4S fishbone diagram, widely used in the service industry, categorizes potential causes into four sections, each starting with the letter ‘S’, namely, surroundings, systems, skills, and suppliers:

• Surroundings include the external environment of your business, such as customers.

• Systems represent the essential internal processes for customer service or product delivery.

• Skills denote competencies necessary for effective job performance, while suppliers involve employees, contractors, and partners collaborating on company projects.

3. 8P fishbone diagram

The 8P fishbone diagram features eight cause sections, each beginning with the letter ‘P’, which are procedures, policies, place, product, people, processes, price, and promotion:

• Procedures: Encompass what is needed for your company to operate.

• Policies: Detail the rules and regulations set by your company.

• Place: Indicate where your company operates from.

• Product: Denote what type of products your company will sell.

• People: Refer to those working for you.

• Processes: Describe how tasks are accomplished within your organization.

• Price: Determine how much you should charge for your products and services.

• Promotion: Outline annual promotional activities.

While its primary use is in the service industry, this variation is adaptable for application in nearly all types of businesses and industries.

4. 6M fishbone diagram

This specific fishbone diagram is predominantly used in manufacturing. It categorizes potential problem causes into six attributes:

• Man/manpower: Encompassing employers and employees involved in designing and delivering a product

• Method: Including the production process, among other procedures, contributing to the final product's delivery

• Machine: Referring to any systems or tools utilized in manufacturing

• Material: Denoting the raw materials and components necessary for creating the end product

• Measurements: Detailing the physical metrics of a product or work unit

• Mother nature: Encompassing internal and environmental factors

Read more: 8 Popular Project Management Tools and What They're Useful For

Related terms

• Agile project management

• Burndown chart

• Gantt chart

• Project plan

• PERT chart

• RACI chart

• Scope creep

• Work breakdown structure

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