An experimental study on change of gas permeability depending on pore structures in three species (hinoki, Douglas fir, and hemlock) of softwood

Journal of Wood Science

Official Journal of the Japan Wood Research Society

Table 2 Results of regression (n = 90)

\(Y = \alpha_{0} + \beta_{1} X_{1} + \beta_{2} X_{2} + \beta_{3} X_{3} + \beta_{4} D_{1} + \beta_{5} D_{2} + \varepsilon\)
Variables	Panel A		Panel B		Panel C		Panel D
Variables	Coef.	t-stat.	Coef.	t-stat.	Coef.	t-stat.	Coef.	t-stat.	VIF
Intercept	− 0.449^*	− 3.688	0.186^*	2.931	2.510^*	5.016	1.568^*	5.232
X₁	3.000^*	9.582	–	–	–	–	2.251^*	5.856	4.082
X₂	–	–	1.955^*	9.135	–	–	0.736^*	2.869	4.017
X₃	–	–	–	–	− 4.316^*	− 3.692	− 4.505^*	− 6.527	1.265
D₁, D₂	Included		Included		Included		Included
adj.R²	64.10%		63.60%		35.90%		78.40%
F-value	53.966		50.076		17.632		65.543
p-value	< 0.001		< 0.001		< 0.001		< 0.001

^* Represents significance at 1 percent level. Denotations of variables are the same as in Table 1