Question:

An experiment was conducted to study the toxic action of a certain chemical on silkworm larvae. The relationship of log₁₀ (survival time) to log₁₀ (dose) and log₁₀ (larvae weight) was investigated. The data, obtained by feeding each larvae a precisely measured dose of the chemical in an aqueous solution and recording the survival time until death, are given in the following table. The data are stored on the attached silkw. file.

Assume the model y = b₀ + b₁x₁ + b₂x₂ +e.

a. Plot the response y versus each predictor variable. Comment on these plots.

b. Obtain the least squares estimates for b and give the fitted equation.

c. Construct the ANOVA table and test for a significant linear relationship between y and the two predictor variables.

d. Which independent variable do you consider to be the better predictor of log(survival time)? What are your reasons?

e. Of the models involving one or both of the independent variables, which do you prefer, and why?