Directed technical change

For many problems in macroeconomics, development economics, tabour economics, and international trade, whether technical change is biased towards particular factors is of central importance. This paper develops a simple framework to analyse the forces that shape these biases. There are two major forces affecting equilibrium bias: the price effect and the market size effect. While the former encourages innovations directed at scarce factors, the latter leads to technical change favouring abundant factors. The elasticity of substitution between different factors regulates how powerful these effects are, determining how technical change and factor prices respond to changes in relative supplies. If the elasticity of substitution is sufficiently large, the long run relative demand for a factor can slope up.