Find Your Root Cause With Fishbone Diagrams



Posted: Sunday, March 15, 2009

by Steve Wilheir
PMP Training Course

A useful tool for completing a root cause analysis on a defined problem is a fishbone diagram. A fishbone diagram encourages team members to work systematically and to look beyond the obvious causes of a problem. The structure of the fishbone diagram allows for potential root causes to be found in a structured manner.

Dr. Kaoru Ishikawa, a Japanese quality control expert, invented he fishbone diagram. It is a type of cause and effect diagram. It is also referred to as an Ishikawa diagram. The diagram resembles the skeleton of a fish which is how it got its popular name Fishbone."

Creating Ishikawa Charts The starting point of the project management root cause study is a dilemma that is to be researched. The dilemma is articulated as an inquiry on the right half of the paper. A sketch of a fish head or an arrow directs you to the relevant inquiry. Left of the articulated dilemma, a horizontal line separates the page into a pair of sections, forming the "spinal column" of the fishbone paradigm.

The following collection of bones stand for the primary types of variables that might play a part in the underlying or root cause. The labels of these subsets are displayed across the upper and lower portions of the page. Arrows lead in the direction of the spinal column and in the direction of the head, creating a herringbone look.

When it comes to managing and appropriating issues for problem domains, there are often quick and easy tricks to remember where to start. For example, manufacturing would use the "6 M's", service and administrative problems would use the "8 P's", service may also use the "4 S's", and more modern analysis also has its own categories.

Analysis gets underway after the fundamental skeletal structure is in position. Variables are listed that play a part in each subset of elements that result in the underlying or root cause. These are displayed on top of arrows directing you to the subset lines, which themselves may possess lines of their own directing toward them, further delineating the variables that play a part. While this may proceed ad infinitum, naturally it will be hard to sketch more than a minimal number of levels.

With the skeleton of the diagram in place a team brainstorms about each category, looking for reasons that produce the end result. Generally, it is good to phrase a problem as a question and ask team members to answer the question in the context of each category. In general, the question is "Why is this happening?" Then, for each category, the question shifts to "How are factors in this category causing this?"

The brainstorming continues until team members can no longer think of useful items to add to the diagram. At this point, the results are analyzed to identify the most likely root causes of the problem. Finding the same issue within multiple categories is a good indication that it is an important root cause in the system. Likewise, areas of the diagram that are densely populated with detail are likely to point to areas of significance.

Steve Wilheir is a project management consultant. Learn more about finding the root cause of your organization's teamwork issues, and learn more about fishbone diagrams and his Project Manager Training
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Top-level comments on this article: (1 total)
» left by Harold Ramos
from Boynton Beach, FL 3 years 37 days ago.
I'm going to send this around the office.  We coudl really use more of this where I work.  I think it would be nice to know if there were any type of fishbone software that could help me making the fishbone charts.
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