"The authors develop an endogenous growth model that combines structural change with repeated product improvement. That is, the technologies in one sector of the model become not only increasingly capital-intensive, but also progressively productive over time. Application of the basic model to...

That Lima's water system was in near-crisis was not enough to bring about radical change. Partial reforms to reduce many of the city's worst problems were carried out under public management. But a quarter of Lima's citizens still had no access to water or sewerage connections, extended service...