Research on the Stability of NDGM Model with the Fractional Order Accumulation and Its Optimization

Table 2

The fitted values and MAPE of four grey models (unit:  ton-km).

Year	Actual value	DGM	NDGM
2002	1549.12	1549.12	1549.12	1549.12
2003	1817.44	1899.10	1807.62	1811.13
2004	2398.13	2374.15	2426.34	2418.20
2005	3068.30	2968.18	3041.35	3048.45
2006	3644.14	3710.85	3652.70	3648.96
MAPE		2.65	0.71	0.49
2007	4098.42	4639.35	4260.39	4212.31
2008	4707.50	5800.16	4864.46	4741.86
2009	5154.46	7251.42	5464.90	5242.83
MAPE		25.70	4.44	1.74