We look for the scale effects on growth predicted by some theories of trade and growth based on dynamic returns to scale at the national or industry level. The increasing returns can arise from learning by doing, investment in human capital, research and development, or development of new products. We find some evidence of a relation between growth rates and the measures of scale implied by the learning by doing theory, especially total manufacturing. With respect to human capital, there is some evidence of a relation between growth rates and per capita measures of inputs into the human capital accumulation process, but little evidence of a relation with the scale of inputs. There is also little evidence that growth rates are related to measures of inputs into R&D. We find, however, that growth rates are related to measures of intra-industry trade, particularly when we control for scale of industry.
In a world with two similar, developed economies, economic integration can cause a permanent increase in the worldwide rate of growth. Starting from a position of isolations, closer integration can be achieved by increasing trade in goods or by increasing flows of ideas. We consider two models with different specifications of the research and development sector that is the source of growth. Either form of integration can increase the long-run rate of growth if it encourages the worldwide exploitation of increasing returns to scale in the research and development sector.