Limitations of Why Why Analysis
In our book 'Implementing ISO 9001:2008 Quality Management System', we mentioned 'Why why Analysis' as a tool for adding value to internal QMS. We clearly mentioned - "Do not see who is responsible. Rather consider why and what caused the problen or nonconformity. ..... Find out fundamental cause of the nonconformity and stop it happening it again. We need to ask WHY? WHY? WHY? We should not ask -- WHO? We provided examples for using Why Why method. Basically Why Why Analysis is a simple and useful technique, however we need to know its limitations.
Many in the industry know the root cause analysis system called the 5 Whys or Why Why Analysis. It was created at Toyota and has been implemented in many other organizations that use lean manufacturing concepts. Unlike some of the more complex root cause analysis systems, 5 Whys does not require any data segmentation, regression, testing of hypotheses or other high end statistical tools. In many instances, using the 5 Whys can be done without any data collection either.
Five Whys technique is a popular technique for root cause analysis. Many people use it. Is this a suitable technique for teams? Do we have any alternate better technique for the teams? John Allspaw, SVP of Technical Operations at Etsy favors to discard Five Whys approach. He says that using the Five Whys is a good first step toward doing real root cause analysis but asking too many whys end up in blaming people.
The idea
is by asking ‘why?’ at least five times, one can peel away many layers of
symptoms and get to the root cause at last of a problem. At many organizations,
the 5 Whys is still important for solving problems, and is the basis of the
scientific approach there. In their experience, repeating ‘why?’ 5 times will
usually reveal the nature of the problem.
The idea of solving a problem means that identify the root cause of problems and then come up with and implement solutions to eliminate the root cause and to prevent them from happening again.
There are following reasons for the criticism of Why Why Analysis:
- Tendency for investigators to
stop at symptoms rather than going on to lower-level root causes
- Inability to go beyond the
investigator’s current knowledge – cannot find causes that they do not already
know
- Lack of support to help the
investigator ask the right “why” questions
- Results are not repeatable –
different people using 5 Whys come up with different causes for the same
problem
- Tendency to isolate a single
root cause, whereas each question could elicit many different root causes
- Considered a linear method of
communication for what is often a non-linear event
- Problem
with the 5 Whys is that it does not always uncover the root cause when the cause
is not known. Also, the 5 Whys presumes that each symptom has one cause. This
is not always true, so this type of analysis does not always show several
sufficient causes that are causing the symptom.
- How well
the 5 Whys works depends some on the skill of the person using it. If one why
has an incorrect answer, it can throw off the entire analysis. Last, this
method is not always repeatable. Three people applying the 5 Whys can often
come up with different answers.
- Other
disadvantages include the inability of this method to tell between causal
factors and the root cause, and a lack of rigor where the user is not mandated
to do sufficiency testing.
Courtesy Sources
- Implementing ISO 9001:2008
Quality Management System - A Reference Guide, Dr. Divya Singhal and Keshav Ram
Singhal, PHI Learning Private Limited, New Delhi (Available at Amazon)
- Limitations of the Five Whys Technique in Agile Retrospectives, Savita Pahuja - Please CLICK
- Limitations of 5 Whys in CAPA and Root Cause Analysis - Please CLICK
- Keshav Ram Singhal
