THE EFFECTS OF SAMPLE SELECTION BIAS ON RACIAL-DIFFERENCES IN CHILD-ABUSE REPORTING

Objective: The aim was to examine whether design features of Wave 1, 1 980 National Incidence Study (NIS) data resulted in sample selection b ias when certain victims of maltreatment were excluded. Method: Logist ic regression models for the probability of child abuse reports to the child protective services (CPS) were estimated using maximum likeliho od methods for Black (n = 511) and White (n = 2499) child abuse cases. The models were estimated with and without correction for selection b ias using a two-step procedure proposed by Heckman. Results: Substanti al differences were found in the characteristics of Black and White vi ctims by source of report and by type of maltreatment. Also found were sizeable differences within each racial group between sampled agencie s and nonsampled agencies. Sample selection bias affected the estimati on of both White and Black child abuse reporting rates. In the Black s ample, however, the effect of sample selection bias was to reduce the statistical significance of the impacts of reporting agency and physic al and sexual abuse on report rates. In the White sample, most signifi cant factors in the basic model remained statistically significant wit h correction for selection bias. Conclusions: Selection bias was found to be caused by the exclusion of family, friends, and neighbors in th e NIS sample design. Such exclusion has the effect of altering the int erpretation of the determinants of child abuse reporting among Blacks, but not among Whites. Thus, conclusions about racial differences in c hild maltreatment must be reached cautiously, given the NIS study desi gn. (C) 1998 Elsevier Science Ltd.