Question

A study examined the alertness benefits of higher caffeine intake. In the​ study, the researchers investigated the link between daily caffeine intake and alertness at work ​(measured on a 6​-point scale where 1 equals​"not alert​" and 6 equals​"very alert​"). Participants for the study were those who used a popular social networking Web site. Of the​ respondents, those who had very high or very low intakes were​ excluded, leaving a sample size of 49 respondents.

Do the data represent a population or a sample?

A. The data represent a population since the data are all the units that are the subject of the study
B. The data represent a sample since the data are a subset of units.
C. The data represent a population since the data are a subset of units.
D. The data represent a sample since the data are all the units that are the subject of the study.

Answer 1

B. The data represent a sample since the data are a subset of units.

True, we have a sample and all the elements on this sample are subset for the units of the population.

Explanation:

We need to remember that the population represent all the possible elements or individuals of interest and by the other hand the sample is a subset of the population that is used to analyze patterns in the population of interest

Let's analyze one by one the options.

A. The data represent a population since the data are all the units that are the subject of the study

False, we have a sample size n =49 not all the possible elements of the population for this case we don't have a population.

B. The data represent a sample since the data are a subset of units.

True, we have a sample and all the elements on this sample are subset for the units of the population.

C. The data represent a population since the data are a subset of units.

False, by definition the population CAN'T be a subset of the sample size, and that's not the case.

D. The data represent a sample since the data are all the units that are the subject of the study.

False, the data is a sample BUT are not all the units for the study because that only occurs when we have a population.