Table 4. The estimated parameters and fit statistics of the models to predict merchantable log utility rate to total stem volume for long-length logs (MVL).

Equation	Type	Model	Parameter	Estimate	S.E.	t-value	Pr > |t|	R2	Sy·x	n
(3)	dob	MVL1	a1	−2.0888	0.3247	−6.43	<0.0001	0.5415	0.1388	163
			a2	3.5698	0.3310	10.78	<0.0001
	dib	MVL2	a1	−1.8658	0.2248	−8.30	<0.0001	0.5412	0.1334	163
			a2	2.6586	0.2321	11.45	<0.0001
(4)	dob	MVL3	a1	−6.2078	5.2818	−1.18	0.2416	0.5471	0.1384	163
			a2	2.4365	0.2864	8.51	<0.0001
			a3	3.0126	0.2771	10.87	<0.0001
	dib	MVL4	a1	−6.6103	3.8999	−1.69	0.0920	0.5713	0.1293	163
			a2	1.6314	0.1955	8.34	<0.0001
			a3	2.2663	0.1872	12.11	<0.0001