3.1.2T Cause and Effect Analysis

(3.1.2T.P1)

This problem-solving technique is a way to analyze complex problems that appear to have many interrelated causes. One of the key aspects of the technique is the use of a cause-and-effect diagram. Because of the appearance of the diagram, this technique is also called a Fishbone Diagram. (Another name you might hear for this technique is an Ishikawa Diagram. This is named for Kaoru Ishikawa, a Japanese professor who first utilized the diagram in 1943.)

Benefits of this technique include:

  • It allows various categories of causes to be explored.

  • It encourages creativity through a brainstorming process.

  • It provides a visual image of the problem and potential categories of causes.

Developing the Fishbone Diagram (3.1.2T.P2)

Use the following process to create a Fishbone Diagram:

 

Role

Developing a Fishbone Diagram

1

Project Manager, Team Members

Describe the problem

Describe the problem on the far right side of the diagram. This may be the actual problem or it may be a symptom – at this point you are not exactly sure.

2

Project Manager, Team Members

Create the “backbone”

Draw a long horizontal arrow pointing to the box. This arrow will serve as the backbone from which further major and minor causes will be categorized and related.

3

Project Manager, Team Members

Identify major cause categories and tie along the backbone

Identify potential causes and group them into major categories. Examples of major categories include people, processes, material, equipment, environment, etc. The major categories are identified using brainstorming techniques, so at this point you are not worried if there is disagreement about whether a category holds the potential cause or not. Just put them all up. Make sure to leave enough space between the major categories on the diagram so that you can add minor detailed causes in later. Each of these major categories will be explored in more detail.

4

Project Manager, Team Members

Look for more detailed causes for each category

Continue to brainstorm the causes by looking at more detailed explanations for each of the major cause categories identified above. Write the more detailed causes on slanted lines that hook up to the appropriate major category lines.

5

Project Manager, Team Members

(Optional) Look for additional causes for the details

Sometimes, the detailed causes will have other, more granular causes coming off of them. If so, connect additional lines to the detailed lines. Three levels of detail is usually the practical limit for this diagram.

6

Project Manager, Team Members

Analyze and prioritize the causes

When you are done brainstorming major categories and more detailed potential causes, begin analyzing the information you have compiled. Evaluate each major cause and the potential detailed causes associated with it. Remember that the original list was compiled by brainstorming where all ideas are included. Now, you must determine which items seem like they are more likely to be the cause (or one of the causes). Circle the items that are most promising and should be investigated further.

7

Project Manager, Team Members

Determine which areas have the most impact and best chance of success

If there is not an obvious consensus on the top areas to investigate, use some sort of voting system to formally narrow down the top choices with the most chance of success.

8

Project Manager, Team Members

Create an action plan for resolving the circled causes.

Remember that there may be a number of potential causes that interact together to create the problem. The action plan must account for these interdependencies. If the detailed causes are still complex, or if not enough information is known, they may be assigned to one or more people for further analysis outside of the meeting.

Other Rules for the Cause and Effect Session (3.1.2T.P3)

Use these additional rules and techniques in your session.

  • Make sure everyone agrees on the problem you are trying to resolve. The brainstorming process can become chaotic and confusing if people are trying to resolve different problems.

  • Use formal brainstorming techniques to gather the initial lists of major categories and detailed causes. All ideas should be included. Discussion should be limited to understanding the ideas – not reviewing them to see if they are valid or not.

  • There may be a tendency to jump from major categories to solutions. Make sure that you explore all major and detailed causes before you turn to problem solving.

  • Make sure the entire group can see the Fishbone Diagram so that connections and relationships are visually apparent.

  • Don’t let the diagram get too cluttered. If one category starts to dominate the chart, it can be moved to a second diagram.

  • Be aware of detailed causes that come up repeatedly in different major categories. This could be a sign of a root cause.