Comfy wonders whether there are differences across pairs of cities that receive the same discount.
a. Find a 95% confidence interval for the difference between the mean amount spent in Tucson and the similar mean in San Diego. (These means should include the “0 purchases.”) Repeat this for the difference between Phoenix and Santa Fe and then between Riverside and Albuquerque. Does city appear to make a difference?
b. Repeat part a, but instead of analyzing differences between means, analyze differences between proportions of customers who purchase something. Does city appear to make a difference?