22 of the cases (7.6%). Reports by witnesses can be qualitatively different from self-report and might be susceptible to increased error (e.g., exaggeration or fabrication) or underestimation (e.g., compare results in Chang, et al., 1999). On the other hand, adding these 22 subjects to the analyses may have increased predictive power by retaining some of the more affected children. These children were in kin care for a variety of reasons, including maternal drug and alcohol abuse. It was not possible to assess relations with outcomes in 22 cases alone for lack of power. If collaborative kin retrospective reports did underestimate mothers’ use, as results from Chang et al. (1999) might suggest, this would have made it more difficult to identify significant relations between prenatal alcohol exposure and outcomes. However, the fact that the predictive validity for several outcomes increased when the 22 cases were added, compared to the analyses of biological mothers alone, suggested that kin report is valid and did not introduce significant error.
