Section 01. 5 Whys


01. 5 Whys

Overview

5 Whys is commonly listed more as a Lean tool than Six Sigma because it isn't rigorously data-based, but it can be particularly useful, especially to Belts that get trapped in the minutia and don't step back to see the bigger picture (see "Other Options"). The simple idea is to keep asking "Why" (usually five times) to ensure that the root cause(s) to the effects are fully understood. The reasoning is that the result of each time the Why is asked gives a different answer, in essence peeling back the onion as follows:

  • First WhySymptom

  • Second WhyExcuse

  • Third WhyBlame

  • Fourth WhyCause

  • Fifth WhyRoot Cause

A simple fictitious example demonstrates use of the tool well. A problem in London's Trafalgar Square is that Nelson's Column requires frequent, expensive repairs.[1]

[1] The original source of this example is unknown. The example appears in various guises related to many national landmarks in Europe and the U.S.

First WhyWhy does the column need frequent, expensive repairs?

AnswerFrequent washing is damaging the stone.

Obvious solutions in this case include investing in less abrasive cleaning mechanisms and perhaps different detergents. However, this still doesn't reduce the frequency of washing.

Second WhyWhy does it need to be washed so much?

AnswerThere is a build up of pigeon droppings.

Pigeons are a popular sight in Trafalgar Square and obvious solutions in this case might include investing in a pigeon-scaring device or placing devices to stop pigeons landing on the column. Unfortunately pigeons are arguably part of the tourist attraction itself, so this could be difficult to implement.

Third WhyWhy are the pigeons gathering on top of the column?

AnswerThe pigeons eat the spiders on the column.

Obvious solutions might include spraying the column regularly with pesticide to kill the spiders. The use of pesticides is frowned upon at the best of times in a highly populated area, but on such a visible landmark there could be major opposition. Also, the impact of the pesticide on the stone itself would have to be examined.

Fourth WhyWhy are there spiders on the column?

Answer: The spiders eat the insects on the column.

The solution to the third Why still seems to work. The pesticide would kill both the spiders and the insects.

Fifth WhyWhy are the insects there?

AnswerThey are attracted to the brightly lit surface in the evening.

Proposed solutionDelay turning on the lights for 30 minutes and they are attracted elsewhere.

A project example of using 5 Whys in the middle of a sequence of root cause analysis is illustrated in Figure 7.01.1. The problem related to delays in the New Product Introduction (NPI) process. After statistical analysis of the data, the issue is identified to be associated with missing parts on the circuit board. At this point, the Team used 5 Whys (with data to back up each Why) to discover a root cause, which is a design error. Clearly this isn't an end in itself, because a solution to "Design Error" isn't immediately obvious and hence subsequent data collection and analysis was used to take the problem to solution.

Figure 7.01.1. Example of 5 Whys in a project focused on delays in New Product Introduction (NPI).[2]


[2] Adapted from SBTI's Lean training material.

Other Options

In fact a much stronger use of this tool is to ask "Why do I care?" enough times to relate the issue back to a business level problem. This is incredibly useful in the Define Phase of a project. Commonly when identifying and scoping projects, Belts and Champions latch onto a solution and set that to be the goal of the project, when in reality there might be a better approach to the whole project.

To use the same example mentioned in Chapter 2, "DefineTools Roadmap Applied to the Beginning of All Projects," a hospital client's project was focused on the Prepare visit made by expectant mothers a few weeks prior to the big day. The Team had identified a key Y to be "percent of new mothers given access to the Prepare visit," which is difficult to relate to any major performance metric for the hospital as a whole.

By asking "Why do I care?" a number of times, the thought flow is as follows:

  • First Why More mothers need to go through the Prepare visit.

  • Second Why Education given during the Prepare visit is more readily absorbed than during the birthing visit, and doctors' valuable time is wasted during the birthing visit reworking the education.

  • Third Why New mothers need to understand and retain key learning before they return home.

  • Fourth Why New mothers are the ones who are required to give correct care to themselves and their newborns after they leave the hospital.

  • Fifth Why Sometimes new mothers or babies, after returning home, have to be readmitted to hospital for what are essentially avoidable reasons.

The Prepare visit is in fact a solution to a problem, and the true underlying business issue and associated Y is better defined as the "rate of avoidable returns post partum is too high." This has a clinical impact as well as a business implication to the hospital and clearly brings an entirely new perspective to the problem and hence the project.




Lean Sigma(c) A Practitionaer's Guide
Lean Sigma: A Practitioners Guide
ISBN: 0132390787
EAN: 2147483647
Year: 2006
Pages: 138

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