title: Overall type I error rate and power of multiple Dunnett's tests on rodent body weights in toxicology studies.
abstract: Body weight data are routinely collected in in vivo general toxicology studies, including 2-year carcinogenicity studies, to help assess the overall health of animals. The effect of the compound on body weight is statistically evaluated for each sex separately using a linear trend test or a many-to-one test by Dunnett. These tests are performed either in the framework of a one-factor analysis of variance (ANOVA) or a repeated measures ANOVA. The one-factor ANOVA with Dunnett's test at each time point is a common practice in industry. Although each individual test is conducted at the 0.05 significance level, one wonders about the overall type I error rate and power for performing many individual Dunnett's tests. A simulation study is conducted to answer this question for general toxicology studies of durations 1 month, 3 months, and 2 years. These results provide guidance to managing multiplicity of body weight analysis of general toxicology studies.
authors.affiliation: Global Statistical Sciences, Eli Lilly and Company, Indianapolis, Indiana 46285, USA. w.hoffman@lilly.com
authors.forename: Wherly P
authors.initials: WP
authors.lastname: Hoffman
authors.forename: Justin
authors.initials: J
authors.lastname: Recknor
authors.forename: Cindy
authors.initials: C
authors.lastname: Lee
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D051381:Rats; D011916:Rats, Inbred F344; D012107:Research Design; D014116:Toxicology / Q000379:methods*