Page 111 - Six Sigma Advanced Tools for Black Belts and Master Black Belts

OTE/SPH
OTE/SPH
JWBK119-08
Current and Future Reality Trees
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CRT entity Page Ellipse Entity from
UDE
connector connector another page
Figure 8.1 Flowchart shapes used in drawing up a CRT.

information to kick-start the construction of the CRT. Reorganization of the ideas is
required every now and then throughout the whole process.
The third step is to translate the items into CRT entities. These are flowchart shapes.
The commonly used CRT entities are shown in Figure 8.1.
First, assign the UDEs. Recall that typically all whys are UDEs by definition (Figure
8.2). Then add the entities to the UDEs as shown in Figure 8.3.
Next, rearrange the boxes to remove redundancy. In Figure 8.3, W3 and N2 are the
same and one of them can be removed. At this point, you may feel that ‘User wasted
time waiting to be served’could be one of the reasons why user feels frustrated, and an
arrow can be added to show the cause-and-effect relationship. Also you may realize
that ‘Operators cannot cope with the number of calls’probably would not cause ‘User
feels frustrated’ but affect the waiting time, so the arrow can be shifted to point to the
right box. The result is shown in Figure 8.4.
Now select a branch and start expanding it. Add causes to each branch, refine the
statement if needed, and test the cause--effect relationship using if--then statements. If
the cause--effect relationship is insufficient, add the ellipse connector (if two or more
causes need to happen together to bring about the effect) or additional condition
(Figure 8.5),
Next re-examine the CRT, asking the following questions:

1. Are the UDEs appropriate and sufficient? That is, are they bad enough to be called
UDEs,andwilladdressingthemsuccessfullyenablethegoaltobereached?Remove
any inappropriate UDEs and add new ones if necessary.
2. Are the cause--effect relationships real and sufficient? That is, if the cause happened,
then will the effect follow? Feel free to move the entities around and add ellipses if
needed.
3. Might anything at a higher level make worse a cause--effect statement at a lower
level? If so, add a negative reinforcing loop. In Figure 8.6, operators cannot cope
with the workload which will likely cause higher turnover rate, so a negative
reinforcing loop is added.

W3. User
W1a. User W1b. User
feels wastes time wastes time
frustrated waiting going through all
the options

Figure 8.2 Assignment of undesirable effects.