Logical Decisions - Classweb
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Logical Decisions - Classweb

Logical Decisions - Classweb Logical Decisions - Classweb

classweb.gmu.edu
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06.07.2013 Views

similar but more complicated if the goal has a multiplicative MUF formula. You can use representatives in all the weight assessment methods except the smarter method and the direct entry method. The AHP method has a tradition of not using representatives, while representatives are often used in the tradeoff and pairwise weight ratios methods. Formulas for MUFs The simplest MUFs compute an alternative's utility for a goal using a weighted average. These are called additive MUFs, since the weighted utilities for each active member are added to obtain the goal utility. LDW allows you to define more complicated MUF formulas that allow interactions if necessary. MUFs with interactions will be discussed on page 9-55. Approaches for Assessing MUFs To define an additive MUF, you must define a scaling constant (or weight) for each measure. Four general approaches have been developed for doing this. The first approach is to have the decision maker directly provide the scaling constants. The second approach is to have the decision maker order the active members from most to least important. The third approach is to have the decision maker provide "importance ratios" that imply the ratios of the weights for two or more active members. The fourth approach is to compute the scaling constants using pairs of simplified alternatives that the decision maker prefers equally. Because the decision maker prefers the alternatives equally, they should have equal overall utilities. If you define enough pairs, LDW can identify a unique set of weights -- the weights that result in all the pairs having equal overall utilities. LDW provides five different assessment methods that let you carry out these approaches: ! You can directly enter the scaling constants, 9-36 Section 9 -- In Depth

! You can use the "Smarter Method" to have LDW compute weights based on your ordering of the importances of the active members, ! You can use the "Smart Method" to have LDW compute the weights on "swing weights," ! You can define "Tradeoffs" between pairs of active members that LDW helps you select, ! You can define the "Weight Ratios" between pairs of active members, or ! You can use the "Analytic Hierarchy Process." The smarter method uses the importance ordering approach. The smart, weight ratios and analytic hierarchy process methods use the importance ratios approach. The tradeoff method uses the comparisons of alternatives approach. The direct entry method, of course, carries out the direct entry approach. However, you can also interpret the directly entered scaling constants as probabilities that partially define pairs of equally preferred alternatives. This interpretation is discussed further below. The importance ordering, importance ratios and alternative comparisons approaches are all discussed in more detail below. Assessing Weights Using Importance Orderings The "Smarter" method lets you define the weights for the active members using a simple ordering of their relative importances. The method is very easy for decision makers to use and results in a fairly robust set of weights. The Smarter method is often a good starting point before using a more sophisticated method. When using the smarter method, you can encourage the decision maker to think about the member's ranges by providing the following scenario: Suppose you had an alternative that had the least preferred level on all of the active members. And further suppose that you could improve just one active measure from its least preferred to its most preferred level. Which active member would you choose to improve. Section 9 -- In Depth 9-37

similar but more complicated if the goal has a multiplicative MUF<br />

formula.<br />

You can use representatives in all the weight assessment methods<br />

except the smarter method and the direct entry method. The<br />

AHP method has a tradition of not using representatives, while<br />

representatives are often used in the tradeoff and pairwise weight<br />

ratios methods.<br />

Formulas for MUFs<br />

The simplest MUFs compute an alternative's utility for a goal<br />

using a weighted average. These are called additive MUFs, since<br />

the weighted utilities for each active member are added to obtain<br />

the goal utility. LDW allows you to define more complicated<br />

MUF formulas that allow interactions if necessary. MUFs with<br />

interactions will be discussed on page 9-55.<br />

Approaches for Assessing MUFs<br />

To define an additive MUF, you must define a scaling constant (or<br />

weight) for each measure. Four general approaches have been<br />

developed for doing this.<br />

The first approach is to have the decision maker directly provide<br />

the scaling constants.<br />

The second approach is to have the decision maker order the<br />

active members from most to least important.<br />

The third approach is to have the decision maker provide<br />

"importance ratios" that imply the ratios of the weights for two or<br />

more active members.<br />

The fourth approach is to compute the scaling constants using<br />

pairs of simplified alternatives that the decision maker prefers<br />

equally. Because the decision maker prefers the alternatives<br />

equally, they should have equal overall utilities. If you define<br />

enough pairs, LDW can identify a unique set of weights -- the<br />

weights that result in all the pairs having equal overall utilities.<br />

LDW provides five different assessment methods that let you<br />

carry out these approaches:<br />

! You can directly enter the scaling constants,<br />

9-36 Section 9 -- In Depth

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