Business Cycles and the Relationship between Concentration and Price-Cost Margins
利用1958-1981年284个制造业行业的新面板数据，发现集中度高的行业价格成本利润率对需求波动更敏感，导致集中与非集中行业利润率差距缩小，表明横截面估计可能有偏。
Using a newly constructed panel data base, we examine changes in price-cost margins in 284 manufacturing industries between 1958 and 1981. A key finding is a dramatic narrowing of the spread between the margins of concentrated and unconcentrated industries over this period. We provide evidence that this narrowing is a result of the greater sensitivity of price-cost margins in more concentrated industries to demand fluctuations. This finding is robust to the inclusion of other industry variables and to measures of import competition. The results indicate that cross sectional estimates of the concentration-margins relationship are likely to be both biased and misleading.