Fernando del Rio

Vintage Capital and the Dynamics of the AK Model

This paper analyzes the equilibrium dynamics of an AK-type endogenous growth model with vintage capital. The inclusion of vintage capital leads to oscillatory dynamics governed by replacement echoes, which additionally influence the intercept of the balanced growth path. These features, which are in sharp contrast to those from the standard AK model, can contribute to explaining the short-run deviations observed between investment and growth rates time series. To characterize the optimal solutions of the model we develop analytical and numerical methods that should be of interest for the general resolution of endogenous growth models with vintage capital.

Embodied technological change learning-by-doing and the productivity slowdown

The productivity slowdown faced by the US economy since the first oil shock has been associated with a rise in the decline rate of the relative price of equipment and a reduction in the rate of disembodied technical change. We build up a growth model in which learning-by-doing is the engine of both embodied and disembodied technological progress. A change in the relative efficiency of learning-by-doing from the consumption to the investment sector is shown to imply a technological reassignment consistent with the above mentioned evidence. This result derives from the interaction between the obsolescence costs inherent to embodiment and the learning-by-doing engine.

Complementarity, Linkages between Firms, and the Effect of Entry Costs on Productivity

In a general equilibrium model where firms are heterogeneous in terms of productivity, we introduce differentiated goods in production that are not perfect substitutes, as well as intermediate inputs needed to produce those goods. We show that an increase in either the complementarity of differentiated goods or the share of intermediate inputs in gross output, significantly increases the negative effect of entry costs on total factor productivity (TFP) and output per worker. We also find that the effect of complementarity is quantitatively stronger. If we assume an empirically plausible value for the elasticity of substitution between differentiated goods, then the model considerably improves its ability to reproduce the observed negative relationship between entry costs and TFP or output per worker.