Aggregate Fluctuations with National and International Returns to Scale*
提出一个模型，其中全球中间产品种类的增加带来规模报酬递增，即使技术冲击只发生在单个国家，也能解释各国产出、要素投入和生产率的正相关波动，并说明双边贸易量与国际经济联动的关系。
Cyclical movements in aggregate output, factor inputs, and productivity are all positively correlated across countries. This article proposes a model in which positive cross‐country correlations of these variables result from increasing returns to the world‐wide variety of intermediate goods even if technology shocks are purely country‐specific. The model also accounts for the observed positive relationship between bilateral trade volume and international comovements. Positive comovements can also arise with constant returns to variety, but only if technology shocks are themselves strongly correlated. The combination of constant returns and common shocks, however, tends to generate procyclical fluctuations of the trade balance.