Recall that psychologists modeled desire to have cosmetic surgery (y) as a function of gender (x1), self-esteem (x2), body satisfaction (x3), and impression of reality TV (x4). The psychologists theorized that one's impression of reality TV will "moderate" the impact that each of the first three independent variables has on one's desire to have cosmetic surgery. If so, then x4 will interact with each of the other independent variables.
a. Give the equation of the model for E(y) that matches the theory.
b. Fit the model, part a, to the simulated data saved in the file. Evaluate the overall utility of the model.
c. Give the null hypothesis for testing the psychologists' theory.
d. Conduct a nested model F-test to test the theory. What do you conclude?
For information: Refer to the Body Image: An International Journal of Research (March 2010) study of the influence of reality TV shows on one's desire to undergo cosmetic surgery, Exercise 12.17.