The fishbone diagram identifies many possible causes for an effect or problem. It can be used to structure a brainstorming session. It immediately sorts ideas into useful categories. It is also a decomposition technique that helps trace an undesirable effect back to its root cause.
Where this technique is applied within PMBOK®?
Within the PMBOK®Guide, Cause-and-effect diagrams Technique is used in the following process:
|PROCESSES||KNOWLEDGE AREA||PROCESS GROUPS|
|Manage Quality||Project Quality Management||Executing|
|Control Quality||Project Quality Management||Monitoring and Controlling|
Cause-and-effect diagrams are also known as fishbone diagrams, why-why diagrams, or Ishikawa diagrams. This type of diagram breaks down the causes of the problem statement identified into discrete branches, helping to identify the main or root cause of the problem.
How to build Fishbone Diagram – Procedure
Materials needed: flipchart or whiteboard, marking pens.
Agree on a problem statement (effect). Write it at the center-right of the flipchart or whiteboard. Draw a box around it and draw a horizontal arrow running to it.
Brainstorm the major categories of causes of the problem. For example, you analyze the causes of project delay in a major project as part of the closure
You can decide to attribute the causes to the knowledge areas of the project management
Write the categories of causes as branches from the main arrow.
Brainstorm all the possible causes of the problem. Ask: “Why does this happen?” As each idea is given, the facilitator writes it as a branch from the appropriate category. Causes can be written in several places if they relate to several categories.
As an example: Changes could be a cause for the delay of the project. Changes could have come in scope, stakeholders, resources. The count of change requests also can be captured to see the magnitude of the cause over the problem
Again ask “why does this happen?” about each cause. Write sub–causes branching off the causes. Continue to ask “Why?” and generate deeper levels of causes. Layers of branches indicate causal relationships.
When the group runs out of ideas, focus attention to places on the chart where ideas are few.
Cause-and-effect diagrams are used to identify the possible effects of quality defects and errors. A specific defect could be the problem with a total number of counts. The root cause categories to be identified. Examples could be Knowledge, lack of standards, tight schedule, lack of reviews etc.
Once the causes are identified translate the number of causes under each category into a histogram. Apply 80:20 rule to prioritize the cause and work on the solution. Let us take an example on change requests. For a given project there were 60 change requests were raised. The categories shall be
- Resource related
The Histogram out of this analysis looks as below. Quality issues are predominant causes for the change request. You can start solving, to begin with, Quality, then schedule etc
PMBOK® GUIDE SIXTH EDITION
Article writer P Seenivasan, PMP, PgMP, PfMP