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

Table 4

Errors by the competitive models in Case 1.

Index	GM (1, 1)	NGM (1, 1, k)	NEGM (1, 1, t^2)	INEGM (1, 1, t^2)
In-sample
MAPE (%)	0.4129	0.2960	0.1456	0.0904
RMSPE (%)	0.0027	0.0011	0.0035	0.0001
MAE	0.3301	0.2382	0.1163	0.0726
MSE	0.1701	0.0716	0.0222	0.0070
IA	0.9675	0.9873	0.9960	0.9987
R	0.9564	0.9819	0.9951	0.9986
Out-of-sample
MAPE (%)	1.0750	1.6552	0.3643	0.3152
RMSPE (%)	0.0192	0.0330	0.0020	0.0015
MAE	0.9039	1.3891	0.3060	0.2646
MSE	1.3616	2.3374	0.1390	0.1051
IA	0.7427	0.4344	0.9495	0.9604
R	0.9618	0.9437	0.9599	0.9599