作者：Davidson, R; Duclos, JY
作者单位：Laval University; Laval University
作者：Kortum, SS
作者单位：National Bureau of Economic Research
摘要：This paper develops a search-theoretic model of technological change that accounts for some puzzling trends in industrial research, patenting, and productivity growth. In the model, researchers sample from probability distributions of potential new production techniques. Past research generates a technological frontier representing the best techniques for producing each good in the economy. Technological breakthroughs, resulting in patents, become increasingly hard to find as the technological...
作者：Kyriazidou, E
摘要：We consider the problem of estimation in a panel data sample selection model, where both the selection and the regression equation of interest contain unobservable individual-specific effects. We propose a two-step estimation procedure, which ''differences out'' both the sample selection effect and the unobservable individual effect from the equation of interest. In the first step, the unknown coefficients of the ''selection'' equation are consistently estimated. The estimates are then used to...
