Toxic effects of copper and zinc

Reference no: EM131012010

Toxic Effects of Copper and Zinc. In a study of the joint toxicity of copper and zinc, researchers randomly allocated 25 beakers containing minnow larvae to receive one of 25 treatment combinations. The treatment levels were all combinations of 5 levels of zinc and 5 levels of copper added to a beaker. Following a four-day exposure, a sample of the minnow larvae were homoge- nized and analyzed for protein. The results are shown in Display 10.20. (Data from D. A. J. Ryan, J. J. Hubert, J. B. Sprague, and J. Parrott, "A Reduced-Rank Multivariate Regression Approach to Aquatic Joint Toxicity Experiments," Biometrics 48 (1992): 155-62.) Fit a full second-order model for the regression of protein on copper and zinc, and examine the plot of residuals versus fitted values. Repeat after taking the log of protein. Which model is preferable?

Reference no: EM131012010

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