Table 6.

Verifying difference significance of coefficients in regression formula.

Factor	Coefficient estimate	df	Standard error	F-value	p-value	Significance
intercept	0.027	1	1.36 × 10−3	-	-	-
X1	−9.37 × 10−4	1	8.35 × 10−4	1.26	0.3124	-
X2	1.25 × 10−5	1	8.35 × 10−4	2.24 × 10−4	0.9886	-
X3	5 × 10−5	1	8.35 × 10−4	3.59 × 10−3	0.9546	-
X1X2	−9.75 × 10−4	1	1.18 × 10−3	0.68	0.4464	-
X1X3	1.50 × 10−4	1	1.18 × 10−3	0.016	0.9038	—
X2X3	6.5 × 10−4	1	1.18 × 10−3	0.30	0.6056	—
X12	−7.32 × 10−3	1	1.23 × 10−3	35.50	0.0019	***
X22	−9.27 × 10−3	1	1.23 × 10−3	56.94	0.0006	***
X32	−7.25 × 10−3	1	1.23 × 10−3	34.78	0.0020	***

^***Values of “Prob > F” less than 0.05 indicates model terms significant.