Chapter 4.1, Problem 27E

To determine

To explain how the sampling method results in under-coverage that could lead to bias.

Explanation of Solution

This would lead to bad sampling method because households which do not have telephones or having telephones but number is not listed in telephone directory are not included in the sampling frame. Here under-coverage occurs because in the population, there are some groups which are left due to the choosing of random sample. Since this method of sampling does not cover entire population this leads bias.