Analyzing the Relationship between the PM_2.5 Concentration and the Gini Coefficient Using the Grey Model

Table 5

Fitting results of the PM_2.5 concentrations in Northwest China.

Year	Shaanxi			Gansu			Qinghai
	Gini coefficient	PM2.5	Result	Gini coefficient	PM2.5	Result	Gini coefficient	PM2.5	Result
2006	0.461	56.10	56.10	0.482	45.90	45.90	0.473	32.40	32.40
2007	0.459	56.10	58.09	0.490	41.50	43.44	0.474	33.60	35.56
2008	0.462	47.80	58.12	0.477	41.00	43.49	0.486	34.50	35.58
2009	0.456	57.80	58.06	0.478	47.00	43.63	0.481	35.20	35.60
2010	0.456	64.40	57.96	0.435	48.40	44.14	0.452	40.20	35.54
2011	0.405	67.50	57.17	0.396	53.80	45.15	0.402	42.00	35.41
2012	0.404	61.20	56.37	0.364	47.70	46.02	0.359	35.70	35.26
2013	0.399	61.40	56.27	0.355	49.20	46.53	0.332	38.80	35.14
2014	0.387	54.30	56.01	0.386	43.00	46.25	0.358	35.90	35.14
2015	0.404	47.00	56.07	0.469	38.70	44.84	0.444	29.20	35.33
2016	0.403	51.10	56.32	0.430	39.80	44.31	0.396	28.50	35.39
MAPE	9.07%			7.87%			8.66%
2017	0.398		56.23	0.427		44.82	0.391		35.30
2018	0.393		56.08	0.424		44.89	0.386		35.28
2019	0.388		55.93	0.421		44.97	0.381		35.27
Year	Ningxia				Xinjiang
	Gini coefficient	PM2.5	Result		Gini coefficient		PM2.5	Result
2006	0.444	60.00	60.00		0.436		54.70	54.70
2007	0.448	44.30	44.79		0.428		58.40	52.99
2008	0.453	38.20	44.80		0.433		52.50	53.29
2009	0.442	46.80	44.80		0.427		48.50	53.09
2010	0.433	53.40	44.78		0.386		61.00	53.13
2011	0.377	51.40	44.73		0.342		51.30	54.32
2012	0.348	45.60	44.67		0.310		55.60	55.60
2013	0.368	47.80	44.66		0.313		60.90	56.96
2014	0.358	40.10	44.67		0.345		59.10	57.40
2015	0.466	39.40	44.74		0.399		49.20	56.57
2016	0.394	40.30	44.77		0.385		53.80	54.25
MAPE	8.77%				5.84%
2017	0.392		44.71		0.382			54.76
2018	0.390		44.71		0.378			54.88
2019	0.388		44.71		0.375			54.99