Table 3. Parameter estimates for equations in Table 2 by species using 5th national forest inventory. All estimated parameters were significantly different from zero (p < 0.005). The result of optimal equation for each tree species were bold type.

Species	Parameters				Performance Criteria
	Model No.	a	b	c	R2	RMSE	MD	AMD	AIC
PD	1	22.600	0.016	0.637	0.426	2.754	-0.001	2.129	183,440
	2	25.627	0.062	0.695	0.426	2.754	-0.001	2.129	183,436
	3	2.834	-9.986		0.408	2.796	0.020	2.158	184,573
	4	120.677	4.71	0.213	0.426	2.754	-0.001	2.128	183,429
	5	0.013	1.79	21.169	0.426	2.754	-0.001	2.129	183,436
	6	24.813	-29.693	12.812	0.425	2.755	0.000	2.129	183,467
	7	36.770	0.041	0.736	0.426	2.754	0.000	2.128	183,434
LK	1	21.755	0.089	1.683	0.527	3.582	0.001	2.833	25,070
	2	21.34	0.025	1.334	0.527	3.582	0.000	2.833	25,072
	3	3.324	-11.288		0.525	3.589	0.001	2.839	25,085
	4	27.032	12.511	1.056	0.525	3.588	0.004	2.84	25,086
	5	0.096	0.349	22.783	0.527	3.582	0.000	0.000	25,069
	6	27.77	-11.1	-0.083	0.525	3.589	0.002	2.84	25,087
	7	23.873	0.01	1.761	0.526	3.583	0.003	0.000	25,074
QV	1	16.111	0.074	1.155	0.477	2.543	0.001	1.955	62,550
	2	15.955	0.052	1.095	0.477	2.543	0.001	1.955	62,549
	3	2.934	-9.189		0.474	2.55	0.007	1.961	62,618
	4	22.045	6.288	0.775	0.476	2.547	0.001	1.957	62,585
	5	0.076	0.784	17.24	0.477	2.543	0.001	1.955	62,549
	6	20.423	-12.008	2.250	0.476	2.546	0.000	1.956	62,547
	7	18.547	0.03	1.368	0.476	2.545	0.001	1.956	62,564
QM	1	14.101	0.079	1.053	0.456	2.309	0.000	1.765	87,892
	2	14.098	0.071	1.026	0.456	2.309	-0.001	1.765	87,893
	3	2.785	-7.819		0.455	2.311	0.003	1.765	87,920
	4	17.781	5.989	0.843	0.456	2.309	0.001	1.765	87,898
	5	0.079	0.927	15.297	0.456	2.309	-0.001	1.765	87,892
	6	17.056	-9.363	1.416	0.456	2.309	0.000	1.765	87,892
	7	15.844	0.039	1.359	0.456	2.308	0.000	1.764	87,886