Materials Prices and Productivity
利用美国普查局企业数据，发现企业间材料价格差异显著，若价格相同，生产率标准差将缩小7%；价格差异具有持续性、空间相关性，并与退出概率正相关，且影响进入退出对生产率增长的贡献。
There is substantial within-industry variation in the prices that plants pay for their material inputs. Using plant-level data from the US Census Bureau, I explore the consequences and sources of this variation in materials prices. For a sample of industries with relatively homogeneous products, the standard deviation of plant-level productivity would be 7% smaller if all plants faced the same materials prices. Moreover, plant-level materials prices are persistent, spatially correlated, and positively associated with the probability of exit. The contribution of entry and exit to aggregate productivity growth is smaller for productivity measures that are purged of materials price variation. After documenting these patterns, I discuss three potential sources of materials price variation: geography, differences in suppliers' marginal costs, and within-supplier markup differences. Together, these variables explain 15% of the variation of materials prices.