A study on properties of GM(1,1) model and direct GM(1,1) model

In this paper, the properties of the GM(1,1) model and the direct GM(1,1) model are studied .The fact that both the GM(1, 1) model and the direct GM(1,1) model are biased exponential models is shown, and the characteristics of the deviation of the two models are analyzed. Therefore, the essence of the error of the GM(1,1) model and the direct GM(1,1) model is clarified. Furthermore, the comparison between the GM(1,1) model and the direct GM(1,1) model is given here. Many valuable results are drawn from the study, which lead to the better application of grey model to its relevant fields.