ALTERNATIVE DEFINITIONS OF DEMAND FOR RECREATIONAL ANGLING IN NORTHERN IRELAND
研究了1988年北爱尔兰休闲垂钓总需求中三种需求定义对估计参数的影响，发现基于个人访问次数的方法在统计和用户效益估计上更优。
The effects of three alternative definitions of demand on estimated parameters are explored in a travel‐cost study of aggregate demand for recreational angling in Northern Ireland in 1988. Functions are estimated using individual visits and zonal visitation rates for the number of visits and the number of visitors as alternative demand definitions. The approach using individual visits was found to be the more satisfactory in statistical terms and in relation to estimates of user benefits when compared with a parallel contingency valuation study. It is judged to be the more appropriate approach where there is a well defined and quantifiable user group. However, the modelling of income and substitutes in the functions proved to be unsatisfactory, perhaps due to inadequate specification and measurement of these variables.