Saponification of Jatropha curcas Seed Oil: Optimization by D-Optimal Design

Table 3

Regression coefficients of the predicted quadratic polynomial model for response variables 𝑌 (FFA%).

Variables	Coefficients (𝛽) %	𝑡	𝑃	Notability
	FFA (𝑌)
Intercept linear	96.65	144.21	0.0001	***
𝑋1	17.28	889.81	0.0001	***
𝑋2	4.33	57.02	0.0001	***
𝑋3	1.91	9.52	0.0150	**
Square
𝑋11	−15.14	130.05	0.0001	***
𝑋22	0.37	0.085	0.7777
𝑋33	0.63	0.33	0.5838
Interaction
𝑋12	−3.48	30.63	0.0006	***
𝑋13	−1.40	4.02	0.0800
𝑋23	0.11	0.023	0.8825
𝑅^2	0.99

^∗∗𝑃<0.05; ^∗∗∗𝑃<0.01. T: 𝐹 test value
See Table 2 for a description of the abbreviations.