We test for a change in the volatility of 215 US macroeconomic time series over the period 1960-1996. We find that about 90% of these series have experienced a break in volatility during this period. This result is robust to controlling for instability in the mean and business cycle...

This paper develops a model that examines the effect of monetary policy uncertainty on trend growth. It is assume that the provision of potentially productive public goods and services is financed by money creation (seignorage). Uncertainty derives from stochastic fluctuations in money supply....

This paper presents a simple stochastic growth model in which productivity improvements are the result of both internal (deliberate) and external (serendipitous) learning behaviour. The model is used to illustrate how these different mechanisms of endogenous technological change can lead to...