Use a 4S fishbone to identify potential causes of a problem.
The 4S fishbone organizes potential causes into the following categories.
  • Suppliers
  • Systems
  • Surroundings
  • Skills


  1. Gather the project team and appropriate stakeholders for a brainstorming session.
  2. For each category, list all possible causes or process inputs. You can create secondary categories for the primary categories, then list the causes or process inputs under the secondary categories. If the standard categories of the causes are not appropriate for the problem, create new ones. Fishbone diagrams can include any type of cause that you want to investigate.
  3. Identify the most important causes.

You can quickly brainstorm ideas in the brainstorming list, then drag them to the diagram to create associations between related ideas. For more information, go to Generate a brainstorm list.