Table 4.

The regression coefficients.

Region	$\widehat{\mathrm{y}}={\beta }_{\mathrm{0}}+{\beta }_{\mathrm{1}}{x}_{\mathrm{1}}+{\beta }_{\mathrm{2}}{x}_{\mathrm{2}}+{\beta }_{\mathrm{3}}{x}_{\mathrm{3}}$
	β 0	β 1	β 2	β 3
Dongbei	6.6077	−0.0238	−0.0535	−0.0517
Huabei	5.8204	−0.0225	−0.0388	−0.0393
Huadong	5.9147	−0.0197	−0.0366	−0.0520
Huazhong	4.6873	−0.0197	−0.0300	−0.0303
Xibei	5.3413	−0.0251	−0.0312	−0.0312
Nanfang	4.9882	−0.0301	−0.0311	−0.0306