Grey Forecasts of Combination Model-GM(2,1) and Time-series

For non-monotonic oscillations and saturated S-shaped sequence, it proposed the GM(2,1) and time series combined model while the residual sequence meeting the conditions of residual modeling. Through EViews software, the residual sequence of GM(2,1) was analyzed, time series model were set, and then time-series model and the GM(2,1) combined were combined. Demonstrated by an example, it indicated that the simulation accuracy and prediction accuracy of the combined model have more significantly improvement than the GM(2,1) model does.