91影视

We are given some sampling plans and we have to find which sampling plan is for estimating the proportion of all adults in a medium-sized town who favor a tax increase to support the local school system does not suffer from undercoverage bias.

Undercoverage bias means the samples which does not give or represents the full sample.

(a) A random sample of $250$names from the local phone book. in this sample some people who may not be listed in phonebook due to some law enforcement. and in this condition there may be people who favour tax increase creating a bias.

(b) A random sample of $200$parents whose children attend one of the local schools. This sample does not include adults who don't have children who attend local schools, therefore this will be considered as undercoverage bias.

(c) A sample consisting of $500$people from the city who take an online survey about the issue . This sample does not include adults who don't use online surveys.

(d) A random sample of $300$homeowners in the town . It is not necessary that every adult would be homeowners.

(e) A random sample of $100$people from an alphabetical list of all adults who live in the town . This sample can be considered as undercoverage bias as it will have all adults, where some may not favour tax increase.

Hence, option (e) is correct.