Table 3.

Significance of regression equation coefficients for the DH and AOP yield rate.

Variable	DH				Yield Rate
	Regression coefficients	Standard error	t-value	p-value	Regression coefficients	Standar d error	t-value	p-value
X1	−0.8936	0.1810	6.6025	0.0002	−0.7163	0.3971	3.4050	0.0143
X2	0.9445	0.1678	9.5353	0.0001	0.8618	0.3682	5.6358	0.0005
X3	−0.9864	0.1810	19.8892	0.0001	−0.9785	0.3971	15.7214	0.0001
X4	0.8830	0.1678	6.2399	0.0002	0.8729	0.3682	5.9345	0.0004
X1X1	−0.9631	0.1810	11.8620	0.0001	−0.9332	0.3971	8.6124	0.0001
X2X2	−0.0965	0.1678	0.3214	0.7891	−0.7757	0.3682	4.0760	0.0052
X3X3	−0.7736	0.1810	4.0490	0.0054	0.0447	0.3971	0.1484	0.9016
X4X4	−0.6767	0.1678	3.0486	0.0247	−0.6691	0.3682	2.9863	0.0272
X1X2	−0.6401	0.2365	2.7632	0.0381	0.5982	0.5189	2.4761	0.0584
X1X3	−0.7468	0.2365	3.7247	0.0088	0.1339	0.5189	0.4480	0.7097
X1X4	0.6998	0.2365	3.2492	0.0182	0.0667	0.5189	0.2216	0.8536