Factor substitution, average firm size and economic growth

This paper extends the Lucas (1978, The Bell Journal of Economics 9(2), 508-523) analysis of firm size by taking into account a normalised aggregate CES production function. In a general equilibrium framework it is proved that there is an inverse relation between the elasticity of substitution and average firm size. If interpreted together with the fact that richer countries are characterised by a higher elasticity of substitution, this result can explain why the recent literature finds a positive association between the importance of SMEs in an economy and its stage of development, but seems to fail in finding causality between the two. Both have a common origin: a high value of the elasticity of substitution. This paper also provides a first empirical test of the theory proposed using cross-country data from both developed and developing countries.