Table 6.

ANOVA analysis for response surface quadratic model.

	Sum of squares	df	Mean square	F value	P value	Significance
					Prob > F
Regression	63.6369	9	7.0708	7.7595	<0.001	***
Residual	12.7574	14	0.9112
Lack of fit	6.6542	9	0.7394	0.6057	0.0758	NS
Pure error	6.1032	5	1.2206
Total	76.3943	23

(NS): nonsignificant at the level 95%.