Table 2.

Estimates and Model Fit of Digit Span Functional Form in the Full PSID-CDS Sample

PSID-CDS, Forward Digit Span						PSID-CDS, Backward Digit Span
Functional Form		Model 1	Model 2	Model 3	Model 4	Model 1	Model 2	Model 3	Model 4
Linear	b	0.355	1.214	2.121		0.405	1.166	1.701
	SE	0.009	0.048	0.168		0.008	0.036	0.115
	Lower CI	0.337	1.119	1.792		0.390	1.096	1.475
	Upper CI	0.373	1.309	2.451		0.420	1.237	1.927
	p-value	<.001	<.001	<.001		<.001	<.001	<.001
	AIC	512736363				473110830
	BIC	512736391				473110858
Quadratic	b		−0.038	−0.128			−0.034	−0.087
	SE		0.002	0.016			0.002	0.012
	Lower CI		−0.043	−0.159			−0.037	−0.110
	Upper CI		−0.034	−0.097			−0.031	−0.064
	p-value		<.001	<.001			<.001	<.001
	AIC		503916653				463232157
	BIC		503916689				463232196
Cubic	b			0.003				0.002
	SE			0.000				0.000
	Lower CI			0.002				0.001
	Upper CI			0.004				0.002
	p-value			<.001				<.001
	AIC			503165648				462856581
	BIC			503165692				462856628
Logarithmic	b				3.738				4.154
	SE				0.087				0.064
	Lower CI				3.567				4.028
	Upper CI				3.908				4.280
	p-value				<.001				<.001
	AIC				505770650				464665537
	BIC				505770679				464665565

Note: Missing data were handled using multiple imputation, and baseline cross-sectional sampling weights were used. PSID-CDS child age range: 3–19 years. Bolded values indicate best fitting models.