Table 2.

Model Comparison Test Based on Constraining Birth Order Coefficients to be Equal Between Male and Females (481 Males and 465 Females)

Coefficient tested	CFI	TLI	RMSEA	Chi-Square Test for Difference Testing
				Value	DF
Research expedient
Young on academic standing	0.989	0.985	0.031	3.689	1
Only on substance use	0.986	0.981	0.034	9.755 *	1
Middle on substance use	0.991	0.988	0.027	1.126	1
Young on substance use	0.992	0.989	0.026	0.514	1
Model with combined constraintsa	0.989	0.986	0.029	5.935	3
Full non invariant model	0.991	0.988	0.027
Adler’s
Second on academic standing	0.988	0.984	0.030	3.104	1
Young on academic standing	0.987	0.982	0.032	4.722 *	1
Only on substance use	0.987	0.982	0.031	4.993 *	1
Second on substance use	0.991	0.988	0.026	0.000	1
Middle on substance use	0.990	0.987	0.027	0.534	1
Young on substance use	0.991	0.988	0.026	0.024	1
Model with combined constraintsb	0.990	0.987	0.026	3.233	4
Full non invariant model	0.990	0.986	0.028
Family size
Young on academic standing	0.985	0.982	0.028	3.805	1
Only on substance use	0.986	0.983	0.028	3.902 *	1
Second small on substance use	0.989	0.987	0.025	0.457	1
Second/med/large on substance use	0.988	0.986	0.025	1.060	1
Third small/med/large on substance use	0.989	0.986	0.025	0.778	1
Young on substance use	0.989	0.987	0.024	0.005	1
Model with combined constraintsc	0.986	0.983	0.028	6.990	5
Full non invariant model	0.988	0.986	0.025

^*p<0.05.

^aConstraining young on academic standing, middle, and young on substance use.

^bConstraining second on academic standing, second, middle and young on substance use.

^cConstraining all variables tested except only on substance use.

Notes. All models were nested in and compared to the full non-invariant model. All constraints in coefficients are set to be equal coefficient for male and female adolescents.