13.11 Smart shopping carts. Smart shopping carts are shopping carts equipped with scanners that track the total price of the items in the cart (real-time feedback). To help understand the smart shopping cart’s influence on spending behavior, a group of researchers designed a two-factor study. Each participant was randomly assigned to either be on or not on a budget of $35. Also, each participant’s cart was equipped with or without real-time feedback. The total amount spent on a common grocery list was the response.7

  1. (a) Construct a plot of the means and describe the main features of the plot.

  2. (b) Analyze the data using a two-way ANOVA. Report the F statistics, degrees of freedom, and P-values. Because the nij are not equal, different software may give slightly different F statistics and P-values.

  3. (c) Write a short summary of your findings.