Prediction of China’s Sulfur Dioxide Emissions by Discrete Grey Model with Fractional Order Generation Operators

Table 1

The fitted values and MAPE of different discrete grey models (unit: $ billion).

Year	Actual value			Modified
			(%)		(%)		(%)
1994	51.620
1995	73.597	25.687	65.098	94.227	28.031	82.846	12.567
1996	105.049	34.109	67.530	106.679	1.552	107.697	2.521
1997	139.890	45.294	67.622	120.778	13.662	127.487	8.866
1998	144.959	60.145	58.509	136.740	5.670	143.251	1.178
1999	154.675	79.867	48.365	154.811	0.088	155.805	0.731
2000	165.574	106.055	35.947	175.271	5.856	165.796	0.134
MAPE (%)				9.143		4.333
2001	212.165	140.831	33.622
2002	286.407	187.009	34.705	288.721	0.808	303.083	5.823
2003	403.251	248.329	38.418	407.365	1.020	431.186	6.927
2004	609.932	329.756	45.936	574.762	5.766	594.877	2.468
2005	818.872	437.882	46.526	810.949	0.968	806.887	1.464
2006	1066.300	581.463	45.469	1144.191	7.305	1083.648	1.627
		MAPE (%)		4.846		3.662
MAPE (%)		48.979		7.190		4.028