CASE STUDIES IN BIOMETRY: Chapter 2. Assessing Toxicity of Pollutants in Aquatic Systems A. John Bailer, James T. Oris The file ch2.dat contains the following variables: animal - a unique identifier associated with each C. dubia tested conc - concentration (micro grams/L) brood1 - number of young produced in the first brood brood2 - number of young produced in the second brood brood3 - number of young produced in the third brood total - sum of young produced in the 3 broods (=brood1 + brood2 + brood3)