HOW MANY FIRMS SHOULD BE LEADERS? BENEFICIAL CONCENTRATION REVISITED*
研究了多领导者斯塔克尔伯格模型中赫芬达尔指数与福利的关系，发现长期模型中市场集中度提高反而增进福利，与短期模型结论相反。
This article investigates the relationship between the Herfindahl–Hirschman Index (HHI) and welfare in multiple‐leader Stackelberg models. We formulate two long‐run models of free entry of followers; in the first (second) model, leaders select their output before (after) the entry of the followers. We find that in both models, in contrast to the short‐run models, the Stackelberg model yields a larger welfare and HHI than the Cournot model does regardless of the number of leaders; that is, beneficial concentration always occurs.