Benefit Evaluation of Increments to Existing Systems of Public Facilities
研究了当公共设施系统（如公园）已存在时，如何评估新增设施的边际效益，而非总效益，并指出传统休闲经济学对此关注不足。
Some kinds of public facilities may be categorized as generically similar, with the members of a category having many attributes in common, but also having some distinguishing characteristics. Museums, parks, and many kinds of public recreational an'd cultural attractions come to mind. As systems of generically similar public facilities expand, the issues in benefit estimation change. Consider systems of public parks. These commonly start with one park, or a small number of widely scattered parks, and add sections of quite different environments for public recreational and educational use. When each proposed park can reasonably be considered one-of-a-kind, the benefit evaluation question quite properly is: What is the total benefit of a given area of land as a public park? This question is also the one most commonly considered in the recreation economics literature. However, as the land acquisition and facilities development programs continue, the valuation question becomes: What is the marginal benefit of a given area of land as an increment to an existing park system? The prior existence of a substantial park system is recognized, and the traditional concerns of marginal analysis--for example, diminishing marginal utility, and the existence, quality, and convenience of substitutescome to the fore. These questions have received less attention in the recreation economics literature.1 In this article, we address the general problem of evaluating the benefits of increments to existing systems of public facilities in the context of an empirical case