Labour mobility may be caused by shifts in the derived demand for labour on the part of firms or sectors, or it may be caused by mismatches between workers and their jobs. Both reasons may be important, and this paper merges them into one model. It explores the consequences for (a) wage-tenure relationships and (b) the issue of sluggishness of wages caused by the implied selectivity of workers into preferred jobs and sectors.

This paper explores a model of innovation and spatial competition over time. A key implication of the paper is that firms' size is positively autocorrelated across time. The mechanism that generates this persistence works only in heterogenous-product markets and is based on the idea that larger firms possess better information about the design of future products. Some corroborating evidence is cited.

This paper endogenizes the frequency of major discoveries and the extent of their refinement.Four axioms deliver a one-parameter family of beliefs that guide exploratory effort.Such effort trades off the prospect of major new discovery against the chance of successfully refining discoveries made in the past.The only other parameter is the cost of making new discoveries relative to the cost of refining old ones.The paper derives time-series properties of inventive activity as they relate to the two parameters, and it discusses several specific inventions and their subsequent refinement.In doing so, the paper arguably enhances our understanding of the process of discovery.1 We thank the C. V. Starr Center for Applied Economics for technical and financial assistance.The second

In a model with multiple Pareto-ranked equilibria, we show that the set of equilibria shrinks if we allow trade in assets that pay based on the realization of a sunspot acting as an equilibrium-selection device. When the probability of a low-output outcome is high, the desire to insure against it leads the poor to promise large transfers to the rich in the high-output state. The rich then lose the incentive to exert the effort needed to sustain the high output. Thus the opening of financial markets may destroy the high equilibrium.

Why did the stock market decline so much in the early 1970's and remain low until the early 1980's? We argue that it was because information technology arrived on the scene and the stock-market incumbents of the day were not ready to implement it. Instead, new firms would bring in the new technology after the mid-1980's. Investors foresaw this in the early 1970's and stock prices fell right away. In our model, new capital destroys old capital, but with a lag. The prospect of this causes the value of the old capital to fall right away.

This paper tackles two puzzles: the high empirical elasticity of aggregate output with respect to the measured capital input and the seemingly high variability of growth rates over countries in the medium run. We find that one need not invoke increasing returns or externalities to capital to explain these two puzzles. Rather, they are consistent with a constant-returns-to-scale aggregate production function, so long as the exogenous Solow residual process has enough persistence in it. In our model, casuality runs exclusively from knowledge to capital, and therefore the apparent absence of an external effect to the capital input says nothing about the importance of spillovers in the creation of knowledge.

Early entry has the advantage of higher revenues per unit of output early on. Late entry has the benefit of learning from the experience of earlier entrants, and hence lower production costs. These advantages are balanced off in a continuous time perfect foresight equilibrium. Competition generates S-shaped diffusion, and staggered entry and exit. A monopolist will innovate less than a competitive industry, but the innovation that he does do, he will do sooner.

Early entry has the advantage of higher revenues per unit of output early on. Late entry has the benefit of learning from the experience of earlier entrants, and hence lower production costs. The advantages are balanced off in a continuous-time, perfect-foresight equilibrium. Competition generates S-shaped diffusion, and staggered entry and exit. A monopolist will innovate less than a competitive industry, but the innovation that he does do, he will do sooner.

A paradigm is presented in which both the extent of financial intermediation and the rate of economic growth are endogenously determined. Financial intermediation promotes growth because it allows a higher rate of return to be earned on capital, and growth in turn provides the means to implement costly financial structures. Thus financial intermediation and economic growth are inextricably linked in accord with the Goldsmith-McKinnon-Shaw view on economic development. The model also generates a development cycle reminiscent of the Kuznet hypothesis. In particular, in the transition from a primitive slow-growing economy to a developed fast-growing one, a nation passes through a stage in which the distribution of wealth across the rich and poor widens.