Table 4. Analysis of variance (ANOVA) for fitted models for weight loss of particle board in multiple choice

Source	Sum of squares	df	Mean square	F-value	p-value
Model	4.83	9	0.5367	5.53	0.0371	Significant
X1	0.388	1	0.388	4	0.102
X2	0.2444	1	0.2444	2.52	0.1733
X3	2.26	1	2.26	23.31	0.0048
X1.X2	0.4096	1	0.4096	4.22	0.0951
X1.X3	0.2572	1	0.2572	2.65	0.1644
X2.X3	0.0032	1	0.0032	0.0334	0.8621
X12	0.5912	1	0.5912	6.09	0.0566
X22	0.1956	1	0.1956	2.02	0.2149
X32	0.4485	1	0.4485	4.62	0.0842
Residual	0.4851	5	0.097
Lack of fit	0.3502	3	0.1167	1.73	0.3867	Not significant
Pure error	0.1349	2	0.0675
Cor total	5.32	14

R² = 0.908, adjusted R² = 0.742, predicted R² = –0.128, adequate precision = 9.30, SD = 0.313, coefficient of variation = 31.46, mean = 0.995.
X₁, adhesive concentration (%), X₂, wood vinegar concentrations (%) and X₃, ratio of oil palm trunk and sengon wood sawdust.