We reexamine several bodies of data on the growth of output, labor, and capital, within the context of a model that admits the possibility of an externality to the capital input. The model is an augmented version of Paul Romer's (1987) reformulation of the Solow model. Unlike Romer, however, we...

We examine global dynamics under infinite-horizon learning in New Keynesian models where the interest-rate rule is subject to the zero lower bound. As in Evans, Guse and Honkapohja (2008), the intended steady state is locally but not globally stable. Unstable deflationary paths emerge after...

Aside from the equilibrium that Hotelling (1931) displayed, his model of non-renewable resources also contains a continuum of bubble equilibria. In all the equilibria the price of the resource rises at the rate of interest. In a bubble equilibrium, however, the consumption of the resource peters...

Stock-market crashes tend to follow run-ups in prices. These episodes look like bubbles that gradually inflate and then suddenly burst. We show that such bubbles can form in a Zeira-Rob type of model in which demand size is uncertain. Two conditions are sufficient for this to happen: A declining...

The Q-theory of investment says that a firm's investment rate should rise with its Q. We argue here that this theory also explains why some firms buy other firms. We find that 1. A firm's merger and acquisition (Mamp;A) investment responds to its Q more -- by a factor of 2.6 -- than its direct...

In this paper, our aim is to develop an alternative approach to analyzing a macroeconomic model where markets do not clear. Earlier approaches have had difficulties in interpreting effective demand, a key concept in disequilibrium macroeconomics. We propose a new definition of effective demand...

We ask what level of migration would maximize world welfare. We find that skill-neutral policies are never optimal. An egalitarian welfare function induces a policy that entails moving mainly unskilled immigrants into the rich countries, whereas a welfare function skewed highly towards the rich...

We study the relation between IPO investment and the rate of interest. We model the IPO timing decision and show that the implied relation between interest rates and investment is non-monotonic, and the data support the implication. At low rates of interest firms delay their IPOs. This happens...