| Abstract: | This article discusses statistical parallels between excessive conservatism and insufficient conservatism in rendering forensic opinions. The elements of a tort are reviewed and their relation to psychological and psychiatric opinions is also discussed, as are psychometric and clinical approaches to assessment of impairment and causation in individual lead poisoned children. It is argued that assessments in lead poisoning cases consisting solely of cranial nerve examinations result in considerable Type II Error. Sources of Type II Error in research using analysis of covariance techniques to study the toxic effects of lead include variance stealing, use of excessive numbers of covariates, lack of attention to interactions, and use of covariates that are actually substitute measures of lead ingestion. When experts cite nonsignificant findings of studies of low-level lead exposure, it inappropriately negates lead effects in more severely lead poisoned plaintiffs. In true experimental studies where there is no ambiguity regarding causation, the destructive effects of lead are quite clear. © 1998 John Wiley & Sons, Ltd. |
