PRICES AND ENDOGENOUS MARKET STRUCTURE IN OFFICE SUPPLY SUPERSTORES*
研究了美国办公用品超市价格与市场结构的关系，采用两阶段模型纠正内生性偏差，发现忽略修正项会严重低估竞争对手对价格的影响。
We consider the relationship between prices and market structure for office supply superstores in the U.S. which was central to the Federal Trade Commission's opposition to the merger of Staples and Office Depot. Due to potential biases in a standard regression, we employ a two‐stage approach in which a model of endogenous market structure provides correction terms for a second stage price regression. Using a cross‐section of data on market structures and Staples' prices, we find that excluding the correction term substantially distorts the importance of competitors as the two‐stage model yields stronger negative relationships between prices and market structure variables.