The increase in hazard ratio for Black race following the addition of SES and neighborhood variables indicates that race is in part a marker for low SES and neighborhood factors in the current sample. That is, the lower likelihood of initiating alcohol use in Black vs. White girls is partially attributable to the disproportionate number of Black youth living in low-income households, which has been associated with lower frequency of adolescent alcohol use [21]. The reduction in hazard ratio for childhood trauma similarly indicates that a substantial proportion of the variance in liability to alcohol use initiation attributed to childhood trauma exposure can be accounted for by socioeconomic disadvantage, which has consistently been tied to elevated risk for experiencing trauma during childhood [15,16]. Our hypothesis that childhood trauma that encompasses non-interpersonal events, most notably, witnessing violence, would be more strongly related to SES and neighborhood factors than interpersonal trauma was not supported. We based the hypothesis on the assumption that interpersonal trauma would be less directly related to living in disadvantaged neighborhoods, but descriptions of interpersonal traumatic events experienced by
