Page 109 - Six Sigma Advanced Tools for Black Belts and Master Black Belts

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Current and Future Reality Trees
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The CRT is a logic-based tool for using cause-and-effect relationships to determine
root problems that cause the undesirable effects in a given system. Its purpose is
to depict the state of reality as it currently exists in the system. We often think that
we know the exactly what the problem is, but what we see are only the effects of the
problem and not the true problem itself. This is especially true in transactional projects
where problems are not well defined. The traditional Six Sigma toolset is lacking in
this area to help in defining a project.
The FRT is another logic-based tool, used after the CRT for constructing and testing
potential solutions before implementation. The objectives are to develop, expand,
and complete the solution, and identify and solve or prevent new problems created
by implementing the solution.
In this chapter, we will start by going through the step-by-step procedure for cre-
ating a CRT and an FRT. This will be followed by a discussion of the similarities
and differences and the advantages and disadvantages of the CRT, FRT and their
competitors -- such as failure mode and effect analysis (FMEA) and quality function
3
deployment (QFD) -- in the Six Sigma toolset.

8.2 CURRENT REALITY TREE

In this section, we will show the steps involved in constructing an effective CRT.
Note that this is not the only way this can be done. It is merely one way that has a
simple structure and is easy for beginners to follow. With more experience, users can
develop their own methods to simplify the process. A simple example, concerned
with customer satisfaction with a telephone helpdesk for credit card services, is used
to illustrate the steps.
The first step is to define the system boundaries and goals. This is to make sure the
project is of the right size and to avoid suboptimization. Multiple goals are acceptable
and encouraged to make sure the complete function of the system is captured. In the
case of our example, the boundary is the telephone helpdesk for credit card services,
and the goal is to improve customer satisfaction.
The next step is to identify any undesirable effects (UDEs) and preliminary causes.
UDEs with respect to the goal of the system are identified by brainstorming the causes,
negatives, and whys (in that order).
Negatives can be any indicators that tell you the performance of the system is not up
to expectations. List these negatives (typically between five and ten will be sufficient)
and name them N1, N2 . . . (see Table 8.1).

Table 8.1 List of negatives.
Negatives
N1. Operators cannot cope with the number of calls
N2. User waste time going through all the options
N3. Most of the time still need to talk to operator