TABLE 2.

Associations of Early Maturation and Best Friend’s Deviant Behavior With Problem Behaviors at Age 11 and Their Changes From Ages 11 to 16

Predictor	Delinquency	Physical Aggression	Relational Aggression	Nonphysical Aggression
Effect sizes at age 11 years
Best friend’s deviance	0.09 (0.03 to 0.15)*	0.18 (0.11 to 0.26)*	0.19 (0.13 to 0.26)*	0.27 (0.20 to 0.33)*
Early maturation	0.15 (0.08 to 0.21)*	0.09 (0.03 to 0.14)*	0.05 (−0.02 to 0.12)	0.06 (0.00 to 0.12)
Early × best friend’s deviance	0.07 (0.02 to 0.13)*	0.02 (−0.06 to 0.09)	0.06 (−0.01 to 0.14)	0.03 (−0.06 to 0.13)
Effects sizes on change
Average change per year	−0.47 (−1.71 to 0.76)	0.93 (−0.15 to 2.00)	2.49 (1.32 to 3.65)*	2.14 (0.91 to 3.37)*
Best friend’s deviance	−0.05 (−0.12 to 0.03)	−0.03 (−0.10 to 0.04)	−0.15 (−0.22 to −0.08)*	−0.15 (−0.21 to −0.08)*
Early maturation	−0.06 (−0.13 to 0.01)	−0.08 (−0.14 to −0.03)*	−0.05 (−0.12 to 0.02)	−0.03 (−0.10 to 0.03)
Early × best friend’s deviance	−0.09 (−0.15 to −0.02)*	−0.04 (−0.11 to 0.02)	−0.03 (−0.10 to 0.05)	−0.06 (−0.13 to 0.01)
Model fit
Model χ2(15), P value	61.14, .00	72.82, .00	32.27, .01	46.62, .00
CFI	0.96	0.94	0.97	0.96
RMSEA	0.03	0.04	0.02	0.03
Test of racial/ethnic differences
Δ χ2(18), P value	24.50, 0.14	20.01, 0.33	48.16, 0.00*	30.14, 0.04*

Data are presented as β (95% confidence interval). βs are standardized regression coefficients that can be interpreted as an SD increase in problem behavior associated with early versus not-early maturation, a 1-SD increase in best friend’s deviance, and 1-year increase in age. Covariates in all models include child age at wave 1, family structure, family SES, Spanish used during child and adult interviews, and site. All effects were adjusted for stratification by site, clustering by school, and design and nonresponse weights. *P > .05. CFI, comparative fit index; RMSEA, root mean square error of approximation.