Cause and Effect Diagrams

Cause and Effect diagrams, also known as Ishikawa diagrams or fish-bone diagrams are one of the most commonly used diagramming methods in project management, quality management and risk management. So, if you have decent project management experience/exposure you would’ve seen or used this diagram invariably.

So, what are these Cause & Effect diagrams? These are diagrams that we can use to identify the causes of risks. If you can identify the cause you can not only arrive at a better solution, but also identify other related risks that may go undetected if you did not investigate thoroughly. The purpose may be similar to the root cause analysis technique but it is slightly different. As I said just a few lines ago, if you are a PMP or have been a Project Manager for a while, you would’ve most probably seen this. This and other techniques commonly referred to as the “7 basic tools of quality” are all covered in the “Perform Quality Control” chapter of the PMBOK. We had covered that process in the chapter on Controlling Quality in our PMP exam prep series. You can Click Here to visit that chapter.

If you see the first line of this chapter, I have used 3 different names for this diagram. Frankly speaking they all refer to the same thing but for different reasons. Like:

a. Cause & Effect diagram – As we are attempting to get to the cause of the issue we call it so
b. Ishikawa Diagram – This name is in honor of the gentleman who created this diagram Mr. Kaoru Ishikawa
c. Fishbone Diagram – This name is because it looks like a fish bone.

The diagram shows how various factors may be connected to a potential problem or effect. In our case from a risk management perspective, we will be looking at all the contributing factors to a risk.

Look at the diagram below:



It looks like a tree structure where we are looking to identify or locate the root of the problem. The original problem is on the right hand side and we have identified 4 main causes. Within each cause we have identified a number of sub-causes. As we dig deeper we will be able to narrow down to the heart of the problem.

However, I repeat, all this is from a risk perspective and the problem on the right hand side will usually be a risk and we are breaking down all the causes of that risk using this fish-bone/ishikawa/cause & effect diagram.

Remember that you don’t need to be an expert in all these diagramming methods in order to pass the RMP Examination. But, you need have a good understanding of these topics in order to answer the questions that may be covering these topics.

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