Grey Spectrum Analysis of Air Quality Index and Housing Price in Handan

Table 1

Grey association and cospectrum of AQI and housing price in Handan.

Wave number	P1	P2	P12	Q12	R12	H12	L12	Period
1	0.0525	0.1734	−0.0199	0.0104	0.0555	−0.4821	−1.5347	20.00
2	0.0937	0.1105	−0.0201	−0.0333	0.1463	1.0274	1.6351	10.00
3	0.1520	0.0506	−0.0199	0.0216	0.1118	−0.8258	−0.8761	6.67
4	0.1008	0.0848	0.0077	0.0023	0.0076	0.2901	0.2309	5.00
5	0.1112	0.0847	0.0191	−0.0154	0.0640	−0.6802	−0.4330	4.00
6	0.0784	0.0625	0.0182	−0.0190	0.1411	−0.8088	−0.4291	3.33
7	0.0891	0.0873	0.0403	−0.0123	0.2282	−0.2969	−0.1350	2.86
8	0.1120	0.0471	0.0087	−0.0173	0.0713	−1.1054	−0.4398	2.50
9	0.0744	0.0546	−0.0050	−0.0018	0.0068	0.3426	0.1212	2.22
10	0.0872	0.0571	0.0033	0.0000	0.0022	0.0000	0.0000	2.00

P₁ is the AQI power spectrum, P₂ is the housing price power spectrum, P₁₂ is the grey association between AQI and housing price, Q₁₂ is the grey cospectrum, R₁₂ is the grey condense spectrum, H₁₂ is the grey phase spectrum, and L₁₂ is the grey lag time length.