Logical Decisions - Classweb

percent show destructive interaction, while Ps greater than 50
percent show constructive interaction. Since alternative B is
preferred when P is equal to 50 percent you must make alternative
B less desirable.
You do this by reducing P, so that the probability of getting the
least preferred level on both measures is increased. Since your P
will be less than 50 percent, your answer will show destructive
interaction between the Power and Fuel Economy measures.
To find a particular level for P you can try different probabilities
until you zero in on one that makes alternatives A and B seem
equally desirable. If you try P = 5 percent, you choose alternative
A because the chance of getting your preferred option in
alternative B is too remote. You might feel the same way even if P
= 30 percent. At 40 percent, alternative B still seems preferable to
alternative A. If this is the case, then you might select P = 35
percent as the level of P that makes it most difficult to choose
between alternatives A and B.
7. Answer the probability question by replacing the
default of 50 percent with 35 percent.
8. Click “Equal.”
LDW will use this answer when computing the MUF for the
Performance goal.
LDW computes the utility of the Performance goal using the
multiplicative MUF formula described on page 9-55.
You can see the new scaling constants for performance by
selecting the Review::Weights::Scaling Constants option. In the
table, you will see that the big K for performance is 2.45 and that
the scaling constants for the two members are both 0.35. Since the
scaling constant big K is greater than zero, destructive interaction
is indicated. This is also shown by the fact that the individual
weights (small ks) for the members of the Performance goal (the
Power and Fuel Economy measures) do not sum to one as they do
for the members of the Best Truck goal, which has neutral
interaction.
If we now use the Results::Rank Alternatives option to see the
ranking of the alternatives on the "Buy the Best Truck" goal, we
5-18 Section 5 -- Advanced Tutorial