Table 9. Estimates of regression coefficients for compressive strength (Y₃), with standard error in parentheses.

Variable	IWC		UWC
	SCAD	LASSO	SCAD	LASSO
X1	0.1017	0.1032	0.0972	0.0972
	(0.0000)	(0.0000)	(0.0000)	(0.0000)
X2	0.0322	0.0337	0.0229	0.0299
	(0.0000)	(0.0000)	(0.0000)	(0.0000)
X3	0.0920	0.0931	0.0871	0.0871
	(0.0004)	(0.0003)	(0.0007)	(0.0007)
X4	-0.0866	-0.0802	-0.0494	-0.0494
	(0.0000)	(0.0000)	(0.0000)	(0.0000)
X5	–	0.0173	–	–
	–	(0.0000)	–	–
X6	–	–	–	–
	–	–	–	–
X7	0.0165	0.0174	0.0119	0.0119
	(0.0000)	(0.0000)	(0.0000)	(0.0000)