Question

A bookstore wants to determine how many books the people in the surrounding neighborhood read per month on average. They survey each customer who enters their store for one week. Identify any bias in this method. If appropriate, suggest a method more likely to produce a random sample.

Answer 1

The bias comes from sampling in their own store only. Because there are variable sources to books (libraries, competing bookstores, etc), they should sample at more than one source. Also, the amount of books people read may vary from week to week.

Answer 2

This is biased since they are only questioning people that are entering the bookstore (who are most likely to read, since they are most likely to buy the books and read them). For a more representative group, you need to select other people in the neighbourhood that may not go to the bookstore. Perhaps one could call random houses using a random generator and see how many each person reads, and use a large number number of people.

Answer 3

thanks