. 2020 Jun 26;58(3):902–910. doi: 10.1007/s13197-020-04604-1

Table 2.

Significant^a probability (p values and F-ratio) of the solvent volume, samples weight, and extraction time (independent variables), regression coefficients, R², p value and lack of fit for the reduced response surface model

Regression coefficients	Oil yield
β₀	179.2
β_i	− 7.86
β_j	− 0.0762
β_c	− 34.77
β_ij	0.00829
β_ic	0.853
β_jc	–
β²_i	–
β²_j	–
β²_c	1.943

Main effects				Interaction effects			Quadratic effect
Variables	x_i	x_j	x_c	x_ix_j	x_ix_c	x_jx_c	x²_i	x²_j	x²_c
p value	0.000	0.004	0.000	0.041	0.000	–	^–	–	0.003
F-ratio	51.09	12.37	64.66	5.17	21.89	–	^–	–	13.02
Regression	R²	p value		Lack of fit (F value)			Lack of fit (p value)
Oil yield	0.9283	0.000		4.56			0.056^b

^aOnly the terms with statistical significance are included

^bNon-significant (p > 0.05)