A Dynamic Index Model for Large Cross Sections

This paper shows how standard methods can be used to formulate and estimate a dynamic index model for random fields - stochastic processes indexed by time and cross section where the time-series and cross section dimensions are comparable in magnitude. We use these study dynamic co-movements of sectoral employment in the US economy. The dynamics of employment in sixty sectors is well explained using only two unobservable factors; those factors are also strongly correlated with GNP growth.