Distributions of study variables
The percentage of participants reporting violence involvement items is presented in . Mexican American adolescents were more likely to report several types of violence in comparison to European Americans, but each difference became non-significant when adjusting for socioeconomic status. Of the 222 adolescents who completed surveys at all time points, 46%, 29%, 15%, and 10% reported any victimization at zero, one, two, and all time points, respectively; the corresponding percentages for any perpetration were 54%, 24%, 14%, and 8% (not shown in table).
Distributions of substance use and sexual behavior variables are presented in . At Age 15, 60% of adolescents had ever used alcohol (not shown in table). The number of lifetime sexual partners reported at Age 18 ranged from 0 to 30 (44% reported 0 partners; median=1). At age 19, the number of sexual partners in the past 12 months ranged from 0 to 38 (32% reported 0 partners; median=2). The natural log of number of sexual partners at Ages 18 and 19 was examined in analyses. shows that in comparison to European Americans, Mexican American adolescents were more likely to report sexual experience at age 15 and less likely to report alcohol use at ages 18 and 19. These differences were no longer statistically significant after adjustment for socioeconomic status.
Correlations between study variables
Within and across time points, violence involvement, substance use, and sexual activity variables were significantly associated with one another (see ).
Correlations between study variables.1
Examining whether violence is distinct from sexual activity and substance use
We conducted principal components analyses of study variables within each time point, utilizing Varimax rotation with Kaiser normalization. Two components emerged, corresponding to violence involvement (victimization, perpetration) and other forms of health risk behavior (sexual activity, alcohol, marijuana, and tobacco use). The violence involvement component explained 25%, 29%, and 30% of variance in responses at Ages 15, 18, and 19, respectively, while the sexual activity and substance use composite explained 40%, 38%, and 39% of variance.
Peer violence as a predictor of substance use and sexual activity
shows that adolescents who were victimized by violence at Age 15 were more likely to use tobacco at Age 19 in comparison to adolescents who were not victimized (see Step 1 of Model 1). Adolescents victimized by violence at Age 18 reported a greater number of sexual partners and were more likely to use marijuana at Age 19 (see Step 2 of Model 1). Model 2 shows that adolescents who perpetrated violence at age 18 reported a greater number of sexual partners, engaged in greater alcohol use, and were more likely to use marijuana at Age 19 in comparison to non-perpetrators (see Step 2).
Substance use and sexual activity as predictors of peer violence
shows that sexual behavior, marijuana use, and tobacco use at Age 15 predicted violent victimization and perpetration at Age 19 (see Step 1 of Models 1, 3, and 4). Engagement in sexual behavior and tobacco use at Age 18 predicted violent victimization at Age 19 (see Step 2 of Models 1 and 4). Associations between alcohol use and subsequent violence involvement did not reach statistical significance.
Potential ethnic differences
Potential interactions between predictors and ethnicity were examined for each of the predictors included in Models 1–2 of and Models 1–4 of . Of the resulting 32 interaction tests, only one was significant at p<.05. We do not report this result because it may be due to chance (1/32=.03). The linear regression output of SPSS includes calculations of power based on observed associations between study variables. Power ranged between .05 and .63 for interactions, in contrast to higher levels of power observed for main effects.