Table 4.

Analysis of the variance (ANOVA) of the response surface quadratic model.

Source	Degree of Freedom	Sum of Squares		Mean Square		F-Value		p-Value
		a FFAs	b Yield	FFAs	Yield	FFAs	Yield	FFAs	Yield
Model	9	311.71	143.44	34.63	15.94	379.32	4.53	0.0001	0.0136
Residual	10	0.9131	35.22	0.0913	3.52
Lack of Fit	5	0.2049	18.75	0.0410	3.75	0.2894	1.14	0.9001	0.4452
Pure Error	5	0.7081	16.47	0.1416	3.29
Total	19	312.62	178.66

^aR² = 98.24%; R²_adj = 96.32%. ^b R² = 97.61%; R²_adj = 95.63%.