AVOIDING TYPE-II ERROR IN ASSESSING LEAD TOXICITY PLAINTIFFS

This article discusses statistical parallels between excessive conserv atism and insufficient conservatism in rendering forensic opinions. Th e elements of a tort are reviewed and their relation to psychological and psychiatric opinions is also discussed, as are psychometric and cl inical approaches to assessment of impairment and causation in individ ual lead poisoned children. It is argued that assessments in lead pois oning 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, lac k of attention to interactions, and use of covariates that are actuall y substitute measures of lead ingestion. When experts cite nonsignific ant findings of studies of low-level lead exposure, it inappropriately negates lead effects in more severely lead poisoned plaintiffs. In tr ue experimental studies where there is no ambiguity regarding causatio n, the destructive effects of lead are quite clear. (C) 1998 John Wile y & Sons, Ltd.