Consider again the data in Problem 4.
a. How would you compute appropriate cross-product variables to allow testing of whether an interaction exists between age and faculty rank?
b. State the associated regression model.
c. Using a computer, fit the model. Provide estimates of the regression coefficients.
d. Provide a multiple partial F test for interaction, controlling for age and faculty rank. Use α = .05.
e. Does the F test in part (d) indicate that ANACOVA is valid?
In Problem 4