Aggregation of Space-Time Processes
UCSD Economics Discussion Paper No. 2001-07
30 Pages Posted: 15 Jul 2001
Date Written: May 2001
In this paper we compare the relative efficiency of different methods of forecasting the aggregate of spatially correlated variables. Small sample simulations confirm the asymptotic result that improved forecasting performance can be obtained by imposing a priori constraints on the amount of spatial correlation in the system. One way to do so is to aggregate forecasts from a Space-Time Autoregressive model (Cliff et al., 1975), which offers a solution to the 'curse of dimensionality' that arises when forecasting with VARs. We also show that ignoring spatial correlation, even when it is weak, leads to highly inaccurate forecasts. Finally, if the system satisfies a 'poolability' condition, there is a benefit in forecasting the aggregate variable directly.
Keywords: Spatial Correlation, Aggregation, Forecast Efficiency, Space-Time Models
JEL Classification: C33, C43, C53
Suggested Citation: Suggested Citation