Optimization of Acid Protease Production by Aspergillus niger I1 on Shrimp Peptone Using Statistical Experimental Design

Table 5

Analysis of variance for response surface 2FI model (partial sum of squares, type III).

Source of variation	S.S	D.F	M.S	F value	P-value	Significant
Model	1587.64	6	264.61	19.3708	<0.0001	*Significant
X1	117.43	1	117.43	8.5964	0.0150
X2	3.78	1	3.78	0.2768	0.6103
X3	1191.45	1	1191.45	87.2217	<0.0001
X1X2	1.73	1	1.73	0.1266	0.7294
X1X3	266.67	1	266.67	19.5218	0.0013
X2X3	6.58	1	6.58	0.4816	0.5035
Residual	136.60	10	13.66
Lack of fit	120.77	6	20.13	5.0842	0.0687	Not significant
Pure error	15.84	4	3.96
Total	1724.24	16

S.S: sum of squares; D.F: degree of freedom; M.S: mean square.
*Statistically significant at 95% of confidence level.