title: Confidence interval construction for relative toxicity endpoints such as LD50 or LD90 ratios.
abstract: A common measure of the relative toxicity is the ratio of median lethal doses for responses estimated in two bioassays. Robertson and Preisler previously proposed a method for constructing a confidence interval for the ratio. The applicability of this technique in common experimental situations, especially those involving small samples, may be questionable because the sampling distribution of this ratio estimator may be highly skewed. To examine this possibility, we did a computer simulation experiment to evaluate the coverage properties of the Robertson and Preisler method. The simulation showed that the method provided confidence intervals that performed at the nominal confidence level for the range of responses often observed in pesticide bioassays. Results of this study provide empirical support for the continued use this technique.
authors.affiliation: Risk Education Branch, National Institutional for Occupational Safety and Health, 4676 Columbia Pkwy., Cincinnati, OH 45226, USA. mwheeler@cdc.gov
authors.forename: Matthew
authors.initials: M
authors.lastname: Wheeler
authors.forename: William
authors.initials: W
authors.lastname: Fadel
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Robertson
authors.forename: A John
authors.initials: AJ
authors.lastname: Bailer
mesh_terms: D000818:Animals; D003198:Computer Simulation; D016001:Confidence Intervals; D007313:Insecta / Q000187:drug effects*; D007306:Insecticides / Q000633:toxicity*; D007928:Lethal Dose 50; D008954:Models, Biological; D015233:Models, Statistical
chemical_list: D007306:Insecticides