The Comparison of Treatment with Control Group Means in Toxicological Studies

Three methods of comparing group means in the standard four group toxicological study, where three groups of animals receiving increasing doses of a substance are contrasted with a zero dose control group, are compared by estimating powers using Monte Carlo methods. It is found that, in general, Bartholomew's test for ordered means is the most powerful, but that Williams's test has virtually the same power at detecting effects at the all‐important low dose level.