Let us return once more to the body-mass index (BMI) example for the BRFSS data. We now extend the models involving the explanatory factors of drinking frequency, age, and sleep quality in Chapters 8-9 to consider a model that includes all first-order product terms involving these three factors. Selected output for both models is provided below.
a. Perform and interpret a hypothesis test that evaluates the presence of interaction in this model.
b. If the main interest is to understand the relationship between drinking frequency and BMI, based on results obtained in Section 5.12, is controlling for age and sleep quality necessary?
c. A researcher believes that sleep quality should be controlled for given the results of the hypothesis test shown below. Do you agree with this assessment? What would you say to this researcher?