Table 6.

ANOVA and regression analysis for the response of biomass production (y ₁): optimization of skim milk (% wt/vol) and yeast extract (% wt/vol).

Source of variation	Sum of squire or coefficient estimate	DFa	MS or Std error	F value	P value
Modelb	8.95	4	2.24	2893.35	<0.001
Residual	6.186E − 003	8	7.732E − 004
Lack of fit	4.466E − 003	4	1.116E − 003	2.60	0.1890
Pure error	1.720E − 003	4	4.300E − 004
Total	8.95	12
Factorc
Intercept	7.14	1
x 1	1.01	1	0.011	7889.68	<0.001d
x 2	−6.667E − 003	1	0.011	0.34	0.5732
x 1 2	−0.94	1	0.015	3667.73	<0.001d
x 1 x 2	−0.055	1	0.014	15.65	0.0042d

  ^aDF: degree of freedom.

^b R ² = 99.93%.

^c x ₁, skim milk (% wt/vol), x ₂, yeast extract (% wt/vol).

^dSignificant at α = 0.05.