Although the slope does not measure association, it is useful for comparing effects for two variables that have the same units. For the Internet Use data file of 33 nations on the text CD, let x = GDP (thousands of dollars per capita). For predicting y = percentage Internet penetration (the percentage of adult users), the prediction equation is = 0.1239 + 0.0157x. For predicting y = percentage Facebook penetration, the prediction equation is = 0.081 + 0.0075x.
a. Explain how to interpret the two slopes.
b. For these nations, explain why a one-unit increase in GDP has a slightly greater impact on the percentage using Facebook than on the percentage using the Internet.