Technological variety, technological change and a geography of production techniques
发现美国制造业企业内部生产技术差异很大，且这种差异长期存在，没有向最佳实践收敛的趋势；同一行业不同地区的工厂技术差异显著，并随时间动态变化。
How much heterogeneity in techniques of production exists within the economy, and how does that heterogeneity move over time? In this paper we show that the range of production techniques employed by establishments within individual manufacturing industries is large. We go on to show that technological heterogeneity persists over time: there is no evidence of convergence to best-practice or some other point in technology space. Next, we explore the geography of variety and reveal that there are significant spatial differences in the production techniques employed by manufacturing plants in the same industry. Finally, we examine how these geographical differences move over time, measuring the processes that drive the creation and destruction of the range of production techniques across industries and regions in the US economy. Copyright 2006, Oxford University Press.