Americans are spending an average of two hours and 37 minutes daily on smartphones and other mobile devices to connect to the world of digital information (Business Insider, May 25, 2017). The usage of mobile devices is especially high for affluent, college-educated urban/ suburban dwellers. A survey was conducted on customers in the 50-mile radius of Chicago. Participants were asked the average daily time they spent on mobile devices (Usage, in minutes), their household income (Income, in $1,000s), if they lived in a rural area (Rural =1 if rural, 0 otherwise), and if they had a college degree (College = 1 if college graduate, 0 otherwise). A portion of the data is shown in the accompanying table. 

a. Estimate and interpret a regression model for the mobile device usage based on Income, Rural, College, and the interaction between Rural and College. Explain the rationale for using the interaction variable. 

b. Predict the mobile device usage for a college-educated person with a household income of $120,000 and living in a rural area. What would be the corresponding usage for someone living in a urban/suburban area? 

c. Discuss the impact of a college degree on salary.

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Usage 172 165 ⠀ 110 Income 146 198 # 31 Rural 0 0 ⠀ 0 College 0 1 ⠀ 1