Table 7. Coefficient estimates and related statistics in the third-order model on Y₂

Model term	Coefficient estimate (c0, c1, …, c444)	SE	t-value	p-value
Intercept	5.14667	0.08635	59.6	<0.0001
X1	0.06333	0.05288	1.20	0.2653
X2	–0.19250	0.05288	–3.64	0.0066
X3	–0.39083	0.05288	–7.39	<0.0001
X4	–0.11167	0.05288	–2.11	0.0677
X12	–0.01896	0.03238	–0.59	0.5744
X22	–0.07521	0.03238	–2.32	0.0487
X32	0.08979	0.03238	2.77	0.0242
X42	–0.00646	0.03238	–0.20	0.8469
X1X2	0.00000	0.03739	0.00	1.0000
X1X3	0.01875	0.03739	0.50	0.6296
X1X4	0.01250	0.03739	0.33	0.7467
X1X3	0.12250	0.03739	3.28	0.0113
X2X4	0.06125	0.03739	1.64	0.1400
X3X4	–0.01500	0.03739	–0.40	0.6988
X13	–0.00083	0.02159	–0.04	0.9702
X23	0.08625	0.02159	4.00	0.0040
X33	–0.02667	0.02159	–1.24	0.2518
X43	0.02292	0.02159	1.06	0.3194

Predicted Y₂ = c₀ + c₁ X₁ + c₂ X₂ + c₃ X₃ + c₃ X₃ + c₄ X₄ + c₁₁ X₁² + c₂₂ X₂² + c₃₃ X₃² + c₄₄ X₄² + c₁₂ X₁ X₂ + c₁₃ X₁ X₃ + c₁₄ X₁ X₄ + c₂₃ X₂ X₃ + c₂₄ X₂ X₄ + c₃₄ X₃ X₄ + c₁₁₁ X₁³ + c₂₂₂ X₂³ + c₃₃₃ X₃³ + c₄₄₄ X₄³.