Table 6 Coefficient estimates from the third-order model without interactions

Variable	Parameter estimate	Standard error	t-value	p-value
Intercept	b0=8.83360	0.04816	183.43	<0.0001
D1	a1=0.15174	0.06305	2.41	0.0271
D2	a2=0.03152	0.06305	0.5	0.6232
D3	a3=0.05973	0.06305	0.95	0.356
D4	a4=0.00487	0.06305	0.08	0.9393
D5	a5=–0.10291	0.07722	–1.33	0.1993
X1	b1=0.03475	0.02730	1.27	0.2193
X12	b11=–0.05776	0.01672	–3.45	0.0028
X13	b111=–0.00179	0.01115	–0.16	0.8744
X2	b2=–0.07333	0.02730	–2.69	0.0151
X22	b22=–0.05618	0.01672	–3.36	0.0035
X23	b222=0.03809	0.01115	3.42	0.0031
X3	b3=0.12919	0.04550	2.84	0.0109
X32	b33=–0.03073	0.01672	–1.84	0.0826
X33	b333=0.02497	0.01439	1.74	0.0998
X4	b4=–0.01489	0.04550	–0.33	0.7472
X42	b44=0.04051	0.01672	2.42	0.0262
X43	b444=0.01570	0.01439	1.09	0.2896