An Improved Grey Model with Time Power and Its Application

Table 4

The simulated results and indices by five grey models.

Year	Raw data	GM(1,1)	DGM(1,1)	NHGM(1,1)	GM(1,1, )	OGM(1,1, )
2004	322.6
2005	328.1	329.39	329.53	321.90	328.47	328.40
2006	352.1	347.82	347.96	341.92	345.25	345.35
2007	369.6	367.28	367.42	362.62	365.67	367.40
2008	376.8	387.82	387.97	384.04	388.16	390.72
2009	393.6	409.52	409.66	406.20	411.81	414.38
2010	448.9	432.43	432.58	429.12	436.04	438.11
2011	465.6	456.62	456.77	452.83	460.47	461.79
2012	487.6	482.17	482.31	477.36	484.83	485.39
2013	508.9	509.14	509.29	502.74	508.91	508.92
2014	529.5	537.62	537.77	528.99	532.59	532.38
RMSE		9.21	9.21	10.48	8.55	9.05
MAPE(%)		1.75	1.75	2.23	1.59	1.58
2015	561.8	567.70	567.84	556.15	555.76	555.79
2016	574.0	599.45	599.60	584.24	578.36	579.16
2017	597.5	632.99	633.13	613.30	600.35	602.49
2018	628.0	668.40	668.54	643.36	621.69	625.82
RMSE		29.87	30.02	12.44	25.73	4.78
MAPE(%)		4.46	4.49	1.96	0.83	0.78

The bold values represent the RMSE and MAPE (%) of the model proposed in this paper for model evaluation in the example.