A supermarket compared the average value of purchases made by shoppers who use coupons to the average of shoppers who do not. On average those who use coupons spend $32 more. a. Name several lurking...

A supermarket compared the average value of purchases made by shoppers who use coupons to the average of shoppers who do not. On average those who use coupons spend $32 more.

a. Name several lurking variables that could affect this comparison.²

b. How could the supermarket have avoided confounding caused by possible lurking variables?³

c. An analyst believes that family size is a possible lurking variable. How could the store, with enough data, control for the possible effects of family size on the comparison of the average purchase amounts?⁴