Economists model time as continuous or discrete. The recent literature on continuous time models with delays should help to bridge the gap between these two families of models. In this note, we propose a simple time–to–build model in continuous time, and show that a discrete time version is...

Differential equations with advanced and delayed time arguments may arise in the optimality conditions of simple growth models with delays. Models with investment gestation lags (time-to-build), consumption gestation lags (habit formation) or learning by using lie in this category. In this...

This paper studies a model of car replacement designed to evaluate policies addressed to influence replacement decisions. An aggregate hazard function is computed from optimal replacement rules of heterogeneous consumers, which mimics the hump-shaped hazard function observed for the Spanish car...

A simple dynamic general equilibrium model is set up in which firms face idiosyncratic productivity shocks. Firms whose productivity has fallen too low exit, and entrants try to imitate the best practice of existing firms, so that the expected productivity of entering firms is a function of...

In this paper we analyze the role of replacement and innovation activity in shaping investment behavior and labor productivity in a panel of Spanish manufacturing firms from 1990 to 2001. Investment is concentrated about large investment episodes, or investment spikes, whose nature varies by...

This paper contributes to the literature on both embodied technical progress and firm dynamics, by formulating an endogenous growth model where selection and imitation play a fundamental role in helping capital good producers to learn about the productivity of technologies embodied in new...

A comprehensive study of the linkages between demographic and economic variables should not only account for vintage specificity but also incorporate the relevant economic and demographic decisions in a complete optimal control set-up. In this paper, a methodological set-up allowing to reach...