Association. Suppose you were to collect data for each pair of variables. You want to make a scatterplot. Which variable would you use as the explanatory variable and which as the response variable? Why? What would you expect to see in the scatterplot? Discuss the likely direction and form.

a) Cell phone bills: number of text messages, cost.

b) Automobiles: Fuel efficiency (mpg), sales volume (number of autos).

c) For each week: Ice cream cone sales, air conditioner sales.

d) Product: Price ($), demand (number sold per day).