Agree on the major categories of causes of the problem (written as branches from the main arrow).

Be as clear and specific as you can about the problem. Beware of defining the problem in terms of a solution (e.g., we need more of something).

Major categories often include: equipment or supply factors, environmental factors, rules/policy/procedure factors, and people/staff factors.

fishbone diagram can be helpful in identifying possible causes for a problem that might not otherwise be considered by directing the team to look at the categories and think of alternative causes.

A fishbone diagram is a visual way to look at cause and effect.

The problem or effect is displayed at the head or mouth of the fish.

Brainstorm all the possible causes of the problem. Ask “Why does this happen?” As each idea is given, the facilitator writes the causal factor as a branch from the appropriate category (places it on the fishbone diagram). 

Agree on the problem statement (also referred to as the effect). This is written at the mouth of the “fish.”

Causes can be written in several places if they relate to several categories

Possible contributing causes are listed on the smaller "bones" under various cause categories

It is a more structured approach than some other tools available for brainstorming causes of a problem.

Include team members who have personal knowledge of the processes and systems involved in the problem or event to be investigated