Defining market boundaries
研究利用产品供给和需求的空间信息确定市场的地理范围，提出两种方法（自然市场法和实施法），应用于旧金山湾区医院数据，发现传统方法无法检测的竞争条件差异。
Abstract This study shows how spatial information about product supply and demand can be used to determine the geographic extent of markets. It demonstrates that markets thus defined allow finer‐grained measurement of competitive conditions than is possible using conventional approaches. Two procedures are developed and contrasted: one, called a natural market approach, is drawn from the Industrial Organization economics literature; the second, called an enactment approach, is associated with the open systems perspective on organizations. Applied to a set of hospitals in the San Francisco Bay area, geographic market boundaries established in these ways are shown to lead to finely defined markets, and to reveal strong variation in competitive conditions across the area—variation not detectable if conventional approaches to market definition are used. It is shown that these approaches have applications beyond geographic market definition, and can also be applied to define markets in term of product or service types.