distance in the sample, plus the observed distance form origin i 

 to site j . 



Another methodological option with respect to benefit 

 estimation is the use of the actual intercept rather than the 

 model estimated intercept. Gum and Martin (1975) were the first 

 to utilize an actual intercept in estimating consumer surplus 

 from a recreational demand function. The intercept is the number 

 of trips (quantity demanded) that would be taken at zero price. 

 The reason for using actual instead of predicted trips is that 

 use of the former eliminates the error associated with estimating 

 the intercept. It can be shown that with direct integration of 

 the first stage demand function, only the parameter estimate on 

 distance (travel cost) needs to be utilized from the model; this 

 helps eliminate specification bias. 



In the benefit estimates reported later, net economic values 

 are reported for actual trips, using a modified Gum and Martin 

 Approach. The benefit estimates using predicted intercepts are 

 shown in Appendix C. 



11 



