
Concept explainers
Population vs. Sample (Example 1) In 2017 the Gallup poll surveyed 1021 adults in the United States and found that
a. Identify the population and the sample.
b. What is the parameter of interest? What is the statistic?
a.

Determine the population and the sample.
Answer to Problem 1SE
Population comprises all adults in the U.S., whereas the sample is the 1021 adults surveyed.
Explanation of Solution
The Gallup poll surveyed 1021 adults of the United States in 2017 and found that 57% of them were in favor of a ban on smoking in public places.
A population is a group of objects or people that the researcher wants to study. In the given case, the researcher wants to study the adults’ reaction in the U.S towards the ban on smoking in public places. Hence, the population of the study is ‘all the adults living in the United States’.
A sample is a collection of people or objects taken from the population of interest. As the population of the U.S. is too vast to study, a sample of 1021 adults are surveyed. Hence, the sample of the study is ‘1021 adults surveyed in the U.S’.
b .

Determine the parameter of interest and statistic.
Answer to Problem 1SE
The parameter of interest is the percentage of all U.S. adults who are supporting the ban on smoking in public places, whereas the statistic is the 57% of adults in the sample who are in favor of the ban.
Explanation of Solution
Parameter of interest is a numerical value that characterizes some aspect of the population. Here, the researcher wishes to know the proportion of adults in favor of the ban on smoking in public places in the United States. Thus, the parameter of interest is the proportion of all adults in the U.S. who are in favor of the ban on smoking in public places.
Statistic is a numerical characteristic of a sample of data, which is used to estimate the parameters. In this case, the percentage of adults in the sample who are supporting the ban of smoking in public places, that is 57%, is the statistic.
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