18. What is the equation for a simple linear regression model and how do you interpret the coefficients? 19. What is extrapolation? 20. What are the key words that tell you to use each type of regression? A: Logistic regression? B: Poisson regression? C: Beta regression? D: Polynomial regression? E: Exponential regression? 21. What are the differences between simple, multiple, and multivariate regression? 22. In regression, how do you determine if the interaction term should be included? {3. When do you use a dummy variable? \\