36
Equation (11) is derived with all independent variables held at
their mean (except on-site cost). This includes D1, D2, and D3. Thus,
this relation is based on the average recreationist over all time
periods. If, however, the demand relation for a particular time period
were desired, a zero or one should be substituted for the Di variable.
For example, for time period one all D variables equal zero. The
demand relation for time period one holding all other variables at
means appropriate to time period one, is:
2.198 .051c
y =e
.For period two, D1 is set equal to one and D2 and D3 are zero.
Similarly, for periods three and four, D2 is one and D3 is one,
respectively. If an analysis of recreational values called for a partic-
ular time period, then it is preferable to use values of variables
associated with that period.
By utilizing the mean values obtained.in the demand function a
graphical representation can be derived. The demand function for an
average recreationist, on a per visit.basis, in the Kissimmee River
Basin during 1970 is presented in Figure 3.
The value per visit is based on the theory of consumer surplus
and is the shaded portion of Figure 3. Consumer surplus is based on the
concept that the price a rational person pays for something can never
exceed the price he would be willing to pay rather than do without it.
In many cases the actual price he pays is less than what he would have
paid. The satisfaction that he derives over and above what he gives
up is surplus satisfaction. The measure of this satisfaction is the