Chapter 4.1, Problem 23E

(a)

To determine

To find out the name of this kind of sampling method used in the question.

Answer to Problem 23E

It is cluster sampling method.

Explanation of Solution

Cable companies want to make sure that if they extend their lines to less dense sub urban area then there will be sufficient demands or not so the work will be cost effective.

The given sample is the random sample of five blocks and every family in those blocks are surveyed. Thus, according to this we can say that the sub groups are the blocks while the entire selected sub group is in the sample and that is the cluster formed in sampling. Thus this method has to be cluster sampling method.

(b)

To determine

To give a possible reason why the cable company chose this method.

Explanation of Solution

The cluster sampling is preferred because this method contains mutually exclusive clusters and also this method is more practical and economical and also reduces time of the survey than the other methods. Thus there is a large groups of sample to be surveyed and we cannot use stratified sampling as the stratas formed cannot be more. Therefore the cluster sampling is used for better results.