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...

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...