An Improved Nonequidistant Grey Model Based on Simpson Formula and Its Application

Table 7

Errors by the competitive models in Case 2.

Index	GM (1, 1)	NGM (1, 1, k)	NEGM (1, 1, t^2)	INEGM (1, 1, t^2)
In-sample
MAPE (%)	0.9980	0.2305	0.2103	0.1861
RMSPE (%)	0.0111	0.0008	0.0006	0.0005
MAE	0.1140	0.0260	0.0240	0.0221
MSE	0.0141	0.0010	0.0007	0.0007
IA	0.9916	0.9994	0.9996	0.9996
R	0.9940	0.9996	0.9997	0.9997
Out-of-sample
MAPE (%)	3.6118	6.8170	3.0647	1.6697
RMSPE (%)	0.1790	0.4967	0.1007	0.2208
MAE	0.4925	0.9225	0.4100	0.0758
MSE	0.3409	0.9222	0.7818	0.0758
IA	0.7710	0.4260	0.7818	0.9065
R	0.9823	0.9142	0.9807	0.9815