Table 5.

Estimated regression coefficients and their significance

Source	Estimate	Std. error	t-value	p-value	Remark
Intercept	180.33588	1.995133	90.39	< 0.0001	Significant
X1	6.1529438	0.575945	10.68	< 0.0001	Significant
X2	3.4459979	0.575945	5.98	< 0.0001	Significant
X3	− 7.319777	0.575945	− 12.71	< 0.0001	Significant
X4	3.5297188	0.575945	6.13	< 0.0001	Significant
X1*X2	0.9078531	0.705386	1.29	0.2061
X1*X3	0.0028469	0.705386	0.00	0.9968
X2*X3	− 0.914922	0.705386	− 1.30	0.2026
X1*X4	0.0047281	0.705386	0.01	0.9947
X2*X4	0.7174344	0.705386	1.02	0.3157
X3*X4	2.1051781	0.705386	2.98	0.0050	Significant
X12	0.8420599	0.675356	1.25	0.2203
X22	− 3.375615	0.675356	− 5.00	< 0.0001	Significant
X33	− 2.900884	0.675356	− 4.30	0.0001	Significant
X44	− 3.298121	0.675356	− 4.88	< 0.0001	Significant