Management And Accounting Web

Five Whys Examples

Provided by James R. Martin, Ph.D., CMA
Professor Emeritus, University of South Florida

JIT Main Page | Japanese Management Main Page

Citation: Martin, J. R. Not dated. Five Whys examples. Management And Accounting Web. http://maaw.info/FiveWhysExample.htm

Example 1 - Source Unknown
Machine stopped running
Question Answer
1. Why did the machine stop? It blew a fuse.
2. Why did the fuse blow? The fuse was the wrong size.
3. Why was the wrong size in the fuse box? The engineer put it there.
4. Why did the engineer do that? The supply room issued the wrong size fuse.
5. Why? The stock bin was mislabeled.


Example 2: From Imai, M. 1986. Kaizen. p. 50. (Summary).
Machine stopped running
Question Answer
1. Why did the machine stop? The fuse blew due to an overload.
2. Why did an overload occur? Because the bearing lubrication was inadequate.
3. Why was the lubrication inadequate? Because the lubrication pump was not working right.
4. Why was the pump not working right? Because the pump axle was worn out.
5. Why was it worn out? Because sludge got in it.


Example 3: Based on an Example from Wikipedia*
Vehicle will not start
Question Answer
1. Why will the vehicle not start? The battery is dead.
2. Why is the battery dead? The alternator is not functioning.
3. Why is the alternator is not functioning? The alternator belt has broken.
4. Why is the alternator belt broken? The alternator belt was well beyond its useful service life and not replaced.
5. Why was the alternator belt was well beyond its useful service life and not replaced? The vehicle was not maintained according to the recommended service schedule.
* https://en.wikipedia.org/wiki/5_Whys

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Related summaries:

Deluzio, M. C. 1993. Management accounting in a just-in-time environment. Journal of Cost Management (Winter): 6-15. (Summary).

Deluzio, M. C. 1993. The tools of just-in-time. Journal of Cost Management (Summer): 13-20. (Summary).

Imai, M. 1986. Kaizen: The Key To Japan's Competitive Success. New York: McGraw-Hill Publishing Company. (Summary).

Kristensen, T. B. and P. Israelsen 2012. Management accounting system problems in context of lean: Development of a proposed solution. In Mitchell, F., H. Norrreklit and M. Jakobsen, eds. 2012. The Routledge Companion to Cost Management. Routledge Companions in Business. (Summary).

Martin, J. R. Not dated. Lean concepts and terms. Management And Accounting Web. http://maaw.info/LeanConceptsandTermsSummary.htm

Staats, B. R. and D. M. Upton. 2011. Lean knowledge work: The "Toyota" principles can also be effective in operations involving judgment and expertise. Harvard Business Review (October): 100-110. (Summary).