Stuart Wainwright, the vice president of purchasing for a large national retailer, has asked you to prepare an analysis of retail sales by state. He wants to know if either the percent of male unemployment or the per capita disposable income are related to per capita retail sales. Data for this study are stored in the data file Economic Activity, which is described in the data file catalog in the Chapter 11 appendix.
a. Prepare graphical plots and regression analyses to determine the relationships between per capita retail sales and unemployment and personal income. Compute 95% confidence intervals for the slope coefficients in each regression equation.
b. What is the effect of a $1,000 decrease in per capita income on per capita sales?
c. For the per capita income regression equation what is the 95% confidence interval for retail sales at the mean per capita income and at $1,000 above the mean per capita income?