Table 7.

Average relative errors and Grey correlation degrees of W₁, W₂, W₃ and W₄.

Item	${\mathit{W}}_1$	${\mathit{W}}_2$	${\mathit{W}}_3$	${\mathit{W}}_4$
$\overline{\Delta }$	0.0658	0.0253	0.0687	0.0141
$\eta$	0.9998	0.9923	0.9666	0.9664