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(14)
Welfare Measurement
As noted in the Introduction, a principal purpose of introducing the DS model is to
evaluate its use for the purposes of measuring access value, the take-it-or-leave-it
measure of the worth of recreational opportunities. This welfare measure, when applied
to the value of a particular site, is defined as a change in price from a reference level p3!
to infinity, which causes quantity consumed to change from the baseline level x3! to zero.
Welfare measures for smaller changes in price that leave the individual
consuming the good before and after the price change are also often of interest.
However, because they are straightforward to calculate in the DS model, as with other
models, so they are not pursued further in this paper. Instead, price elasticities of
whalewatching demand at the observed price and quality levels are presented. A similar
approach is taken for quality effects, since they too are straightforward to evaluate in the
DS and other models.
In general the integrability conditions for the model are satisfied for the following
ranges of the income ("3) and own-price (#3) parameters:
(a) "г< 0, #г< 0
(b) " 0, #з< 0
(c) "г> 0, #з < 0
(d) "г > 0, # > "г
For the purpose of measuring access values, in the different parameter ranges the DS
model has characteristics similar to those of the other common demand systems. For