This paper considers unit root regressions in data having simultaneously extensive cross section and time-eries variation. The standard least squares estimators in such data structures turn out to have an asymptotic distribution that is neither Dickey-Fuller, nor normal and asymptotically...

Much macroeconometric discussion has recently emphasised 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...

Traditional empirical strategies for studying convergence - more generally, the dynamics and determinants of economic growth, can be misleading if important, underlying permanent or growth components are stochastically time-varying. This paper documents the degree to which this instability...