Table 1. Gender specific sample characteristics at baseline and of those included in the analytic sample of the general growth mixture modeling (GGMM).

	Baseline (n = 1,339)				GGMM analytic sample (n = 837)
	Males (n = 675)		Females (n = 664)		Males (n = 402)		Females (n = 435)
	n	%	n	%	n	%	n	%
Race/ethnicity
Non-minority	262	39	206	31	129	32	111	26
Minority	413	61	458	69	273	68	324	74
Free lunch in first grade
Paid	331	49	328	49	182	45	195	45
Subsidized or free	341	50	329	50	220	55	240	55
Missing	3	1	7	1	0		0
Peer rejectiona
Almost never	310	46	361	54	211	52	257	59
Rarely	182	27	151	23	126	31	124	28
Sometimes	70	10	48	7	43	11	38	9
Often/always	35	5	24	4	22	4	16	4
Missing	78	12	80	12	0		0
	Mean	95% confidence interval	Mean	95% confidence interval	Mean	95% confidence interval	Mean	95% confidence interval
Aggressive-disruptive problem behavior scorea	2.0	1.9–2.1	1.7	1.6–1.8	2.0	1.9–2.1	1.7	1.6–1.8
Concentration problem scorea	3.2	3.1–3.3	2.9	2.8–3.0	3.1	3.0–3.2	2.8	2.7–3.0
Reading readiness scoreb	27	26.2–26.8	27	26.8–27.4	27	26.2–27.0	27	26.6–27.4

Data were obtained from the Johns Hopkins Prevention Research Center cohort, originally recruited from 19 schools in a Mid-Atlantic school system at entry into first grade in 1985–1986 (age 6) and reassessed as young adults in 2000–2002. The analytic sample included all those with complete baseline information who were successfully assessed in young adulthood (mean age 21)

^aBased on teacher rated report assessed in fall of first grade

^bStandardized reading level based on California Achievement Test Form E&F in first grade, e.g. students at 27th percentile of national average