IHI TOOL: 5 Whys: Finding the Root Cause
Institute for Healthcare Improvement • ihi.org 2
5 Whys: Finding the Root Cause
The key to solving a problem is to first truly understand it. Often, our focus shifts too
quickly from the problem to the solution, and we try to solve a problem before
comprehending its root cause. What we think is the cause, however, is sometimes just
another symptom.
One way to identify the root cause of a problem is to ask “Why?” five times. When a
problem presents itself, ask “Why did this happen?” Then, don’t stop at the answer to
this first question. Ask “Why?” again and again until you reach the root cause.
This simple tool can be surprisingly insightful in helping you figure out what is really
going on, and can help you avoid quick fixes. It is especially useful for tackling chronic
problems that show up over and over again in a complex system.
The technique is attributed to Taiichi Ohno, father of the Toyota Production System,
which revolutionized automobile manufacturing with methods now known as Lean.
It’s important to note that there may be multiple root causes of a problem, and that
different people who see different parts of the system may answer the questions
differently. For a more comprehensive tool, please see Root Cause Analysis
.
Here is an example of how to ask “Why?” five times:
1. Why did the patient receive the wrong medication?
The nurse did not complete patient identification.
2. Why did the nurse not complete patient identification?
The patient did not have a wristband.
3. Why did the patient not have a wristband?
The wristband had been removed for a procedure and not replaced.
4. Why was the wristband not replaced?
The printer for the wristbands was not working.
5. Why was the printer not working?
The staff needed to support IT had been reduced and was overworked.
The problem identified by the fifth “why” is very different from the original event, and
requires a very different solution.
Try it yourself with the worksheet below.
