Numbeo is a crowd-sourced Web site that gathers data on cities and countries around the world (www.numbeo.com/cost-of-living/). Visitors to the site can add information on variables such as cost of living, traffic, and crime. The data are searchable by city or country. For example, when we looked up Halifax, Canada, we discovered that a pair of jeans (“Levis 501 or similar”) goes for an average of $62.50 (Numbeo, 2015). The range was $50 to $75. And a summer dress from somewhere like Zara or H&M goes for an average of $48, with a range of $40 to $60. Numbeo also tells us that their Halifax data are based on contributions from 80 different people.

a. Let’s say that Levi Strauss & Co. agreed to tell you the mean price (in Canadian dollars) of Levi’s 501 jeans around the world. If you wanted to test whether Levi’s 501 jeans in Halifax cost a different amount from the world price, what hypothesis test would you use? Explain your answer.

b. What additional information would you need to conduct the hypothesis test that you identified in part (a)?

c. Thinking back to Chapter 5, what kind of sample is this? What concerns might you have about this kind of a sample?

d. Numbeo doesn’t tell us how many of the 80 contributors answered each of these questions. Why might the sample be even smaller than 80 for the average cost of summer dresses?