These data are the results of an experiment in which different groups of rats were exposed to different concentration levels of ethylene thiourea (ETU), which is a decomposition product of a certain class of fungicides that can be found in treated foods (Graham et al., 1975; Rodricks, 1992, p.133). In this experiment, the outcome of concern was the number of rats that developed thyroid tumors.
A data frame with 6 observations on the following 4 variables.
a numeric vector of dose (ppm/day) of ETU.
a numeric vector indicating number of rats that developed thyroid tumors.
a numeric vector indicating the number of rats in the dose group.
a numeric vector indicating proportion of rats that developed thyroid tumors.
Graham, S.L., K.J. Davis, W.H. Hansen, and C.H. Graham. (1975). Effects of Prolonged Ethylene Thiourea Ingestion on the Thyroid of the Rat. Food and Cosmetics Toxicology, 13(5), 493–499.
Rodricks, J.V. (1992). Calculated Risks: The Toxicity and Human Health Risks of Chemicals in Our Environment. Cambridge University Press, New York, p.133.