Getting to the root of the problem #2

Article: Cause and Effect Analysis - 15 April 2020

Many problems are the result of a number of causes combined together rather than just a single cause. For that reason, Cause and Effect Analysis can help to break down a complex problem into a number of contributory causes. Naturally, the problem becomes easier to understand and overcome once is has been broken down into bite-sized pieces.

Cause and Effect Diagram

Using a Cause and Effect Diagram can greatly assist the analysis. Typically, the diagram is in the shape of a fish skeleton. The head is used to state the problem (or effect), and the bones used to denote causes. Not surprisingly, this tool is often called a Fishbone diagram. It's alternatively known as an Ishikawa diagram (in recognition of its originator Kaoru Ishikawa - a founding father of quality management). Because this diagram helps you trace problems back to their root causes, it therefore leads to improvement from the bottom up.

Cause and Effect diagram

Illustration from a template included in Qudos ISO 9001 Quality Toolkit.

Models of Cause and Effect diagram

The above example is based on the 4S model of cause and effect diagram. The 4S model considers 4 main causal factors. They are: Suppliers, Systems, Skills, and Surroundings. It is typically used in service industries. However, there are also many other models in use. For instance:

  • 4M model for manufacturing companies.This model has factors for: Manpower, Machines, Methods and Materials.
  • 6 category model for manufacturing companies. This model has factors for: Equipment, Process, People, Materials, Environment, and Management.
  • 4 category model for service sector organizations. This model has factors for: Policies, Procedures, People, and Equipment.
  • 8P model for service sector organizations. This model has factors for: Product, Price, Promotion, People, Processes, Place / Plant, Policies, and Procedures.

Some of the listings may seem to be a little contrived. For example, the 8P model looks clumsy in combining Place/Plant as one factor. It does that to keep the factors to an even number. Also, some of the labels also seem to be interchangeable. For instance, Machines and Equipment, or People and Manpower.

Another version of cause and effect diagram is CEDAC. Management systems gurus do seem to love their acronyms. This one stands for "Cause and Effect Diagram with the Addition of Cards". In this model, participants add their ideas on cards or Post-it notes. It is typically used with larger groups. One version of CEDAC uses cards of one colour for causes, and a different colour card for possible solutions.

Performing a Cause and Effect analysis

These models are just some of the more widely used types. However, you are definitely not restricted to them. On the contrary, feel free to adjust the number and scope of categories to be most relevant to your business. Above all, using a cause and effect diagram gives you a structure to focus your thoughts and work within.

You may use a Cause and Effect Diagram when working on your own. While this may be true, it is probably best used collaboratively by a group. The exercise may be conducted online using collaboration software such as Zoom or Teams. That may be necessary in view of current restrictions on meeting face-to-face. Typically, the steps are as follows:

  1. State the effect or problem at the head of the fishbone.
  2. Decide on the primary-level factors. For example, use one of the models mentioned, or brainstorm your own ideas.
  3. Identify causes within each of the factors. Once again, the brainstorming technique can be useful here.
  4. Use the 5 whys techniqueto identify deeper causes (Optional).
  5. Review the findings and adjust as necessary.
  6. After that, plan actions to address the causes.

You may use various other management systems techniques in conjunction with cause and effect analysis. For example, ‘brainstorming’ and ‘the 5 whys’ are already mentioned above. In addition, an Affinity diagram may be used to help you select the primary-level factors.


Author: Alan M. Jones
Qudos Management


Most ISO management system standards (including ISO 9001 and ISO 27001) have a requirement for some form of Root Cause Analysis. Specifically, there is reference in clause 10 'Improvement' to nonconformity and corrective action.

The Qudos ISO 9001 Quality Toolkit also includes tools for Affinity diagrams and brainstorming in addition to template cause and effect diagrams. The toolkit is available online now to Qudos 3 IMS software users and Qudos Club members.

Having read this, you may also be interested in another blog article - Getting to the root of the problem #1 - Root Cause Analysis.