Logical Decisions - Classweb
Logical Decisions - Classweb Logical Decisions - Classweb
A: Wow, that's pretty complicated. It's also hard to see where I'd really be presented with alternatives like this, but I guess I can imagine it. I don't like either of the choices in B very much because I really think a truck should have balanced performance. I don't think I would like to give up so much fuel economy to get really good power or vice versa. So, I'd pick alternative A, where at least I have a chance of getting everything I want. Q: Good, that's the type of interaction I'm trying to get at here. Suppose I make alternative A less desirable. I'll keep everything the same but change the probabilities for A. Suppose the probability of getting the most preferred levels on power and fuel economy was only 25 percent. Would you still prefer alternative A to alternative B? A: No, now I think I'd prefer alternative B in that case. I think I'd have trouble deciding if the probability of getting the most preferred levels was 40 percent. LDW can combine this probabilistic tradeoff between power and fuel economy with the original tradeoffs to compute the scaling constants for a multiplicative MUF formula. Again, the arithmetic is somewhat complicated and won't be described here. Qualitative checks can still be done. The overall utility of alternative A is equal to its expected utility. If there were only two measures, power and fuel economy, the top possibility, with the most preferred level on both measures, would have an overall utility of 1. The lower possibility would have a utility of 0. The expected utility of the lottery is (40 percent)x1 + (60 percent)x0 = 0.4. Both of the possibilities in alternative B would have overall utilities of 0.5 if the two measures were equally important (which we are assuming) and there were no interactions. This would make the overall utility of alternative B also equal to 0.5. However, since A and B were equally preferred, they must have the same overall utility, so interaction must make the overall utility of B less than 0.5. 9-62 Section 9 -- In Depth
A probability of less than 0.5 for the more preferred possibility of alternative A corresponds to the third case in the table above, where big K is greater than 0 and the small k i sum to less than 1. Here, a low utility on any one measure leads to a low overall utility (destructive interaction). Defining Interactions in LDW. LDW lets you define interactions in several ways -- ! By using an additive MUF formula (no interactions). ! By assessing a second tradeoff. ! By assessing a probabilistic tradeoff. ! By directly entering the small k for one measure. ! By directly entering the small k for all measures. Generally, you define interactions after the weights have been assessed. If you define the MUF formula to have no interactions, you don't need to enter any additional information. This is the default. To assess a second tradeoff between two measures, LDW displays a list of the existing tradeoffs and asks you to select one. Then LDW asks you to directly define the second tradeoff using the "free float" tradeoff assessment option. If you have used a weight assessment method other than tradeoffs, LDW will let you select any two active members and define a tradeoff between them. To assess a probabilistic tradeoff, LDW again asks you to select an existing tradeoff. LDW then constructs a probabilistic tradeoff question for the members in the original tradeoff and asks you to enter the probability that makes the two alternatives equally preferred. Again for other assessment methods you can select any two active members to use in the question. Directly entering the small k for one active member lets LDW compute the complete MUF formula. Usually you will compute the small ks using an additive MUF formula first and then select an adjustment. If you enter a small k smaller than the one computed for the additive formula, you will have a big K greater than zero, indicating destructive interaction. Section 9 -- In Depth 9-63
- Page 257 and 258: computed measure levels to common u
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- Page 263 and 264: For an example of the mid-level spl
- Page 265 and 266: Since U(L0) = U(80) = 0 and U(L1) =
- Page 267 and 268: Figure 9-5. Summary of SUF assessme
- Page 269 and 270: describe two alternatives: A, which
- Page 271 and 272: with equal chances of 40 and 70 per
- Page 273 and 274: In the original formulation of the
- Page 275 and 276: 1 Equal Importance Two activities c
- Page 277 and 278: You begin the process by selecting
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- Page 281 and 282: 0.5. Then the weight assigned to "P
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- Page 287 and 288: nth root of the product of the rati
- Page 289 and 290: Figure 9-8. Summary of estimating t
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- Page 303 and 304: Figure 9-14 is an example of the ov
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- Page 311 and 312: Interpreting the Ranking Results LD
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- Page 320 and 321: Buying a House The ranking results
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- Page 333: S E C T I O N Commands Summary 11
- Page 336 and 337: Assess Menu Edit Menu The Assess me
- Page 338 and 339: File Menu Edit::Insert Lets you add
- Page 340 and 341: utility function” if the active g
- Page 342 and 343: Matrix Menu ! Hierarchy -- options
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A: Wow, that's pretty complicated. It's also hard<br />
to see where I'd really be presented with<br />
alternatives like this, but I guess I can imagine it.<br />
I don't like either of the choices in B very much<br />
because I really think a truck should have<br />
balanced performance. I don't think I would like<br />
to give up so much fuel economy to get really<br />
good power or vice versa. So, I'd pick alternative<br />
A, where at least I have a chance of getting<br />
everything I want.<br />
Q: Good, that's the type of interaction I'm trying to<br />
get at here. Suppose I make alternative A less<br />
desirable. I'll keep everything the same but change<br />
the probabilities for A. Suppose the probability of<br />
getting the most preferred levels on power and fuel<br />
economy was only 25 percent. Would you still<br />
prefer alternative A to alternative B?<br />
A: No, now I think I'd prefer alternative B in that<br />
case. I think I'd have trouble deciding if the<br />
probability of getting the most preferred levels<br />
was 40 percent.<br />
LDW can combine this probabilistic tradeoff between power and<br />
fuel economy with the original tradeoffs to compute the scaling<br />
constants for a multiplicative MUF formula. Again, the arithmetic<br />
is somewhat complicated and won't be described here.<br />
Qualitative checks can still be done. The overall utility of<br />
alternative A is equal to its expected utility. If there were only<br />
two measures, power and fuel economy, the top possibility, with<br />
the most preferred level on both measures, would have an overall<br />
utility of 1. The lower possibility would have a utility of 0.<br />
The expected utility of the lottery is<br />
(40 percent)x1 + (60 percent)x0 = 0.4. Both of the possibilities in<br />
alternative B would have overall utilities of 0.5 if the two<br />
measures were equally important (which we are assuming) and<br />
there were no interactions. This would make the overall utility of<br />
alternative B also equal to 0.5. However, since A and B were<br />
equally preferred, they must have the same overall utility, so<br />
interaction must make the overall utility of B less than 0.5.<br />
9-62 Section 9 -- In Depth
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