A Grey NGM(1,1,𝑘) Self-Memory Coupling Prediction Model for Energy Consumption Prediction

Table 3

Comparison of four different models for coal consumption in China (unit: 10,000 ton).

Years	Actual values	GM model		GM + three-point model		NGM model		NGM + self-memory model
		Simulative values	APE𝑡 (%)	Simulative values	APE𝑡 (%)	Simulative values	APE𝑡 (%)	Simulative values	APE𝑡 (%)
1999	139336.46	139336.46	0.00	142733.77	2.44	139336.46	0.00	—	—
2000	141091.70	149528.38	5.98	150048.17	6.35	117190.05	16.94	—	—
2001	144528.11	161279.66	11.59	161587.50	11.80	137509.12	4.86	—	—
2002	152282.66	173954.46	14.23	174286.49	14.45	157579.06	3.48	152937.13	0.43
2003	180587.04	187625.36	3.90	187983.48	4.10	177402.94	1.76	177480.28	1.72
2004	207561.29	202370.64	2.50	202756.91	2.31	196983.77	5/10	213909.03	3.06
2005	231851.07	218274.73	5.86	218691.36	5.68	216324.53	6.70	228641.92	1.38
2006	255065.45	235428.71	7.70	235878.09	7.52	235428.16	7.70	250270.35	1.88
2007	272745.88	253930.81	6.90	254415.50	6.72	254297.57	6.76	272886.66	0.05
2008	281095.92	273886.97	2.56	274409.74	2.38	272935.63	2.90	288069.05	2.48
2009	295833.08	295411.46	0.14	295975.32	0.05	291345.17	1.52	295298.07	0.18
2010	312236.50	318627.53	2.05	319235.71	2.24	309529.01	0.87	315925.57	1.18
2011	342950.24	343668.14	0.21	344324.11	0.40	327489.91	4.51	329093.20	4.04
2012	352647.07	370676.65	5.11	361673.81	2.56	345230.59	2.10	361701.32	2.57
MAPE (%)			5.13		4.93		4.66		1.73

There are no simulative values from year 1999 to 2001 owing to the retrospective order 𝑝=2.