Logical Decisions - Classweb

on the decision maker's response, LDW helps her modify one
alternative until she prefers it equally to the other.
LDW starts the process by showing one alternative having the
most preferred level on the first member and the least preferred
level on the other. The other alternative has the least preferred
level on the first member and the most preferred level on the
second. LDW represents these two alternatives by points at
opposite corners of the graph.
If the decision maker prefers the two alternatives equally, LDW
will assign the two members equal weights. A decrease in the
first member of its entire range just compensates for an increase in
the second member over its range.
If, however, the decision maker prefers the first alternative, the
improvement in the second measure does not compensate for the
change in the first. To make the second alternative more
attractive, we improve its level on the first member.
If we improved the first member all the way to its most preferred
level, the decision maker would have to prefer the second
alternative to the first. It would have the same level (the most
preferred) on the first member and a better level on the second
(the most preferred level vs. the least preferred level).
This means that we can find a level for the first member on the
second alternative that makes the second alternative equally
preferred to the first. A series of questions posed to the decision
maker will allow us to zero in on that level.
For example, suppose that again we want to establish a tradeoff
between Cost and Power for use in selecting trucks. We might do
this by going through the following dialogue with the decision
maker:
Section 9 -- In Depth 9-45