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Posted by Gordon Burditt on 05/06/06 08:32
>However, I don't understand how I would tie in the second question
>about the importance of gas mileage.
>
>Suppose I have the field 'mileage' in the database. All vehicles are
>scored on the 10-point scale depending on how gas-guzzling they are.
>So a Cav is 7, Focus is 7, Civic is 8, Prius is 10, VW TDI is 10, Aveo
>and Echo are 9, Ford F-150 is 2, Humscalade is 1, etc.
>
>How would I tie that question in with the logic is the question asks
>"important" or "not important"? But even before that, what values do I
>give to each radio button of each question?
If something is VERY IMPORTANT, give it a weight of, say, 10.
If something is IMPORTANT, give it a weight of, say 3.
If something is NOT IMPORTANT, give it a weight of about 0.
If something is UNDESIRABLE, give it a weight of, say, -3.
If something is VERY UNDESIRABLE, give it a weight of, say, -10.
The exact numbers are not critical and depend somewhat on how related
the characteristics are. If you multiply all the weights on all
the questions by X (X a positive number), you really haven't changed
anything in the relative ranking.
If you're only going to give two levels of answer, e.g. price:
important or not important, low price should probably have some
positive weight even for those choosing "not important", since "not
important" is not equivalent to "don't care AT ALL" and there's no
other way to say "don't care AT ALL".
Sometimes people consider a feature normally thought of as desirable
as undesirable. For example, HORSEPOWER is often thought of as
good, but if I'm buying a car for my teenage son, it's a NEGATIVE,
as I don't want him to even try hot-rodding with it. Large size
might generally be considered a positive for a large family, but a
negative for a commuter who wants something easy to park in a small
space. I don't know of anyone who thinks good gas mileage is a
negative for their own car except that good gas mileage might imply
non-sportiness. I don't know of anyone who thinks higher price is
a good thing except that low price might imply unreliability.
Gordon L. Burditt
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