Table 5. Coefficient estimates and related statistics in the third-order model on Y₁

Model term	Coefficient estimate (b0, b1, …, b444)	SE	t-value	p-value
Intercept	85.66667	1.43848	59.55	<0.0001
X1	6.03333	0.88089	6.85	0.0001
X2	1.61667	0.88089	1.84	0.1038
X3	1.20833	0.88089	1.37	0.2074
X4	0.15833	0.88089	0.18	0.8618
X12	–1.08229	0.53943	–2.01	0.0797
X22	–1.28229	0.53943	–2.38	0.0447
X32	–5.09479	0.53943	–9.44	<0.0001
X42	0.33021	0.53943	0.61	0.5574
X1X2	0.43125	0.62288	0.69	0.5083
X1X3	–0.40625	0.62288	–0.65	0.5326
X1X4	–0.49375	0.62288	–0.79	0.4508
X1X3	–1.43125	0.62288	–2.30	0.0506
X2X4	–0.89375	0.62288	–1.43	0.1892
X3X4	0.26875	0.62288	0.43	0.6775
X13	–1.22708	0.35962	–3.41	0.0092
X23	–1.18542	0.35962	–3.30	0.0109
X33	2.81042	0.35962	7.81	<0.0001
X43	0.09792	0.35962	0.27	0.7923

Predicted Y₁ = b₀ + b₁ X₁ + b₂ X₂ + b₃ X₃ + b₃ X₃ + b₄ X₄ + b₁₁ X₁² + b₂₂ X₂² + b₃₃ X₃² + b₄₄ X₄² + b₁₂ X₁ X₂ + b₁₃ X₁ X₃ + b₁₄ X₁ X₄ + b₂₃ X₂ X₃ + b₂₄ X₂ X₄ + b₃₄ X₃ X₄ + b₁₁₁ X₁³ + b₂₂₂ X₂³ + b₃₃₃ X₃³+b₄₄₄ X₄³.