Air Pollution and the Public Perception Level and Self-Protection Demand in Three Cities of China: Fractional Grey Modelling Analysis

Table 2

The results of the Baidu index by the FNGMC (1, 2) model in three cities.

	Baidu index	2014	2015	2016	2017	2018	2019	MAPE (%)
Beijing	PM2.5	3286	2749	2838	2603	2130	1626	1.61
	Smog	868	1046	1053	945	746	565	3.93
	Air quality	1721	1738	1948	2071	1865	1423	4.18
Tianjin	PM2.5	515	467	490	451	392	335	1.91
	Smog	289	320	291	239	206	185	1.22
	Air quality	293	302	322	327	310	288	1.64
Shijiazhuang	PM2.5	337	259	308	323	281	222	1.20
	Smog	229	222	210	204	174	138	3.69
	Air quality	185	189	210	228	217	187	1.03