Disclaimer: Use of this tool is not mandated by CMS, nor does its completion ensure regulatory compliance.
Overvi ew: Root cause analysis is a structured team process that assists in identifying underlying factors or
causes of an adverse event or near-miss. Understanding the contributing factors or causes of a system failure
can help develop actions that sustain the correction.
A cause and effect diagram, often called a “fishbone” diagram, can help in brainstorming to identify possible
causes of a problem and in sorting ideas into useful categories. A fishbone diagram is a visual way to look at
cause and effect. It is a more structured approach than some other tools available for brainstorming causes
of a problem (e.g., the Five Whys tool). The problem or effect is displayed at the head or mouth of the fish.
Possible contributing causes are listed on the smaller “bones” under various cause categories. A 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. Include team members who
have personal knowledge of the processes and systems involved in the problem or event to be investigated.
The team using the fishbone diagram tool should carry out the steps listed below.
● Agree on the problem statement (also referred to as the effect). This is written at the mouth of the
“fish.” 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).
● Agree on the major categories of causes of the problem (written as branches from the main arrow).
Major categories often include: equipment or supply factors, environmental factors,
rules/policy/procedure factors, and people/staff factors.
● 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). Causes can be written in several places if they relate to several categories.
● Again asks “Why does this happen?” about each cause. Write sub-causes branching off the cause
● Continues to ask “Why?” and generate deeper levels of causes and continue organizing them under
related causes or categories. This will help you to identify and then address root causes to prevent
● Use the fishbone diagram tool to keep the team focused on the causes of the problem, rather than
● Consider drawing your fish on a flip chart or large dry erase board.
● Make sure to leave enough space between the major categories on the diagram so that you can add
minor detailed causes later.
● When you are brainstorming causes, consider having team members write each cause on sticky notes,
going around the group asking each person for one cause. Continue going through the rounds, getting
more causes, until all ideas are exhausted.
How to Use the Fishbone Tool for Root Cause Analysis