ENTRY AND COMPETITION IN LOCAL HOSPITAL MARKETS*
扩展了Bresnahan和Reiss的进入模型，利用数量数据区分竞争强度变化与固定成本变化，应用于美国医院市场，发现进入迅速导致竞争行为收敛，第二和第三家进入者影响最大。
We extend the entry model developed by Bresnahan and Reiss to make use of quantity information, and apply it to data on the U.S. hospital industry. The Bresnahan and Reiss model infers changes in the toughness of competition from entry threshold ratios. Entry threshold ratios, however, identify the product of changes in the toughness of competition and changes in fixed costs. By using quantity data, we are able to identify separately changes in the toughness of competition from changes in fixed costs. This model is generally applicable to industries where there are good data on market structure and quantity, but not on prices, as for example in the quinquennial U.S. Economic Census. In the hospital markets we examine, entry leads to a quick convergence to competitive conduct. Entry reduces variable profits and increases quantity. Most of the effects of entry come from having a second and a third firm enter the market.