Chapter 14, Problem 22CE

A regional planner is studying the demographics of nine counties in the eastern region of an Atlantic seaboard state. She has gathered the following data:

1. a. Is there a linear relationship between the median income and median age?
2. b. Which variable is the “dependent” variable?
3. c. Use statistical software to determine the regression equation. Interpret the value of the slope in a simple regression equation.
4. d. Include the aspect that the county is “coastal” or not in a multiple linear regression analysis using a “dummy” variable. Does it appear to be a significant influence on incomes?
5. e. Test each of the individual coefficients to see if they are significant.
6. f. Make a plot of the residuals and comment on whether they appear to follow a normal distribution.
7. g. Plot the residuals versus the fitted values. Do they seem to have the same amount of variation?