Mathematical Development and Evaluation of Forecasting Models for Accuracy of Inflation in Developing Countries: A Case of Vietnam

Table 4

The year-on-year inflation variables and forecasting values (%).

Stages	Models	Actual	ARIMA	GM(1,1)	VER	DGM(1,1)	DGM(2,1)	Actual	ARIMA	GM(1,1)	VER	DGM(1,1)	DGM(2,1)	Actual	ARIMA	GM(1,1)	VER	DGM(1,1)	DGM(2,1)
		CPI						RMP						GP
Model building	Feb-13	7.020	7.02	7.02	7.020	7.020	7.020	1.510	1.510	1.510	1.510	1.510	1.510	−1.200	−1.200	−1.20	−1.20	−1.20	−1.20
	Mar-13	6.640	6.490	6.878	6.943	6.888	7.083	1.810	1.879	1.218	1.723	1.230	1.565	−3.470	−3.470	−4.78	−1.97	−4.87	−1.917
	Apr-13	6.610	6.556	6.798	6.849	6.805	7.265	1.700	2.075	1.442	1.973	1.456	1.693	−3.410	−4.485	−5.89	−3.16	−6.00	−3.428
	May-13	6.360	6.441	6.718	6.735	6.723	7.575	1.490	1.752	1.707	2.269	1.723	1.854	−5.830	−5.501	−7.25	−4.91	−7.38	−5.065
	Jun-13	6.690	6.023	6.640	6.598	6.642	8.102	1.640	1.659	2.021	2.623	2.038	2.055	−7.830	−7.539	−8.94	−7.31	−9.08	−6.837
	Jul-13	7.290	7.087	6.563	6.433	6.562	9.001	2.220	2.038	2.393	3.051	2.412	2.307	−13.350	−10.584	−11.01	−10.26	−11.18	−8.755
	Aug-13	7.500	7.297	6.489	6.237	6.483	10.533	2.960	2.797	2.833	3.576	2.854	2.623	−13.430	−13.949	−13.57	−13.47	−13.75	−10.832
	Sep-13	6.300	7.618	6.411	6.008	6.405	13.142	3.550	3.512	3.354	4.232	3.377	3.020	−16.130	−16.675	−16.72	−16.53	−16.92	−13.081
	Oct-13	5.920	4.962	6.336	5.744	6.328	17.587	4.130	3.992	3.971	5.067	3.995	3.517	−22.150	−19.930	−20.60	−19.09	−20.82	−15.515
	Nov-13	5.780	6.541	6.263	5.443	6.252	25.158	4.860	4.668	4.701	6.160	4.727	4.140	−21.400	−23.489	−25.38	−21.00	−25.62	−18.151
Forecasting	Dec-13	—	4.773	6.190	4.743	6.177	60.025	—	4.85	5.57	9.76	5.59	5.90	—	−25.95	−31.27	−23.19	−31.53	−24.09
	Dec-14	—	4.656	6.118	4.352	6.103	97.451	—	4.65	6.59	12.98	6.62	7.13	—	−28.78	−38.53	−23.73	−38.80	−27.44
	Dec-15	—	4.268	6.047	3.945	6.029		—	4.08	7.80	18.49	7.83	8.67	—	−31.62	−47.47	−24.06	−47.74	−31.06
	Dec-16	—	3.963	5.976	3.531	5.957	—	—	3.67	9.24	29.88	9.27	10.60	—	−34.45	−58.49	−24.26	−58.75	−34.98

: error in the model DGM(2,1) of CPI is not shown since its predictions are out of range.