Much macroeconometric discussion has recently emphasized the economic significance of the size of the permanent component in GNP. Consequently, a large literature has developed that tries to estimate this magnitude measured, essentially, as the spectral density of increments in GNP at frequency...

It is often argued that the presence of a unit root in aggregate output implies that there is no "business cycle": the economy does not return to trend following a disturbance. This paper makes this notion precise, but then develops a simple aggregative model where this relation is contradicted....

This paper explores an econometric estimation technique for dynamic linear models. The method combines the analytics of moving average solutions to dynamic models together with computational advantages of the Whittle likelihood. A hypothesis of interest to international and financial economists...

We interpret fluctuations in GNP and unemployment as due to two types of disturbances: disturbances that have a permanent effect on output and disturbances that do not. We interpret the first as supply disturbances, the second as demand disturbances. We find that demand disturbances have a hump...