Use the preparation materials to prepare hand-written answers for the following questions. Please ask any questions on the "Questions -- Preparation Guide" on the course Team (see link on the homepage).
  1. In what order should the variables be entered into the ultimate full model for an IVR?
  2. On what variables should the α, β, δi, and γi coefficients be attached?
  3. How many sub-models are there if the ultimate full model has three indicator (and three interaction) variables? Explain.
  4. How many δi are there in an ultimate full model representing three groups? Explain.
  5. How many γi are there in an ultimate full model representing three groups? Explain.
  6. What does the generic sub-model always look like for the reference group?
  7. What would the generic sub-model look like for the third (of four) groups?
  8. Explain what α, β, δi, and γi measure or represent.
  9. What are the signs (positive, negative, zero) for α, β, δ1, and γ2 if two lines are parallel with a negative slope and the line for the “reference group” is above the line for the other group.
  10. In what order should the explanatory variables be entered into the formula in lm() to fit the ultimate full model for an IVR?
  11. What parameter estimate is found in the row of output labeled with “(Intercept)”? The row labeled with the indicator variable?