The file P11_45.xlsx contains monthly sales for a photography studio and the price charged per portrait during each month. Use regression to estimate an equation for predicting the current month’s sales from last month’s sales and the current month’s price.
a. If the price of a portrait during month 21 is $30, predict month 21 sales.
b. Discuss how you can tell whether autocorrelation, multicollinearity, or heteroscedasticity might be a problem.