Productivity Growth and Machinery Investment: A Long-Run Look, 1870–1980
研究了六个主要经济体过去一个世纪中经济增长与机器投资之间的强关联，认为高机器投资率是长期快速增长的必需前提。
Over the past century in six major economies, economic growth has been strongly associated with machinery investment, as is the case for a larger group of nations since 1950. Both macroeconomic patterns and narratives of the history of technology suggest that this association is causal—that a high rate of machinery investment appears to be a necessary prerequisite for rapid long-run growth—and points away from possibilities that rapid growth is the cause of high machinery investment or that a high rate of machinery investment is a good proxy for other factors that are important causes of growth.