The Shape of Production Functions and the Direction of Technical Change*
从微观基础推导宏观生产函数的性质，发现若思想分布为帕累托分布，则全球生产函数为柯布-道格拉斯形式，且长期技术变迁是劳动增进型的。
This paper views the standard production function in macroeconomics as a reduced form and derives its properties from microfoundations.The shape of this production function is governed by the distribution of ideas.If that distribution is Pareto, then two results obtain: the global production function is Cobb-Douglas, and technical change in the long run is labor-augmenting.Kortum (1997) showed that Pareto distributions are necessary if search-based idea models are to exhibit steady-state growth.Here we show that this same assumption delivers the additional results about the shape of the production function and the direction of technical change.