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 7-point scale where 1-"not alert and 7- 'very alert"). Participants for the study were those who used a popular social networking Web site. Of the respondents, those who had very were excluded, leaving a sample size of 43 respondents. Complete parts a through high or very low intakes c below. b. 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.

A population is the largest group of entire observations that can be made during a study.
A sample is a finite subset of the population that represents the entire population.

Here,

Population = Participants for the study were those who used a popular social networking Web site.

Since the entire data for the "persons used a popular social networking Web site" is not possible.

There have been taken a sample of them.

∴ Correct answer is B. The data represent a sample since the data are a subset of units.