## Basic Definitions and Concepts

Read section 1 from chapter 1 to further enhance your understanding of the elements of descriptive and inferential statistics. This section will introduce some of the key concepts in statistics and has numerous exercise and examples. Complete the odd-numbered exercises before checking the answers.

### EXERCISES

- Explain what is meant by the term
*population*.

- Explain how a sample differs from a population.

- Explain what a
*parameter*is.

- Give an example of a population and two different characteristics that may be of interest.

- Identify each of the following data sets as either a population or a sample:
- The grade point averages (GPAs) of all students at a college.
- The GPAs of a randomly selected group of students on a college campus.
- The ages of the nine Supreme Court Justices of the United States on January 1, 1842.
- The gender of every second customer who enters a movie theater.
- The lengths of Atlantic croakers caught on a fishing trip to the beach.

- Identify the following measures as either quantitative or qualitative:

- The genders of the first 40 newborns in a hospital one year.
- The natural hair color of 20 randomly selected fashion models.
- The ages of 20 randomly selected fashion models.
- The fuel economy in miles per gallon of 20 new cars purchased last month.
- The political affiliation of 500 randomly selected voters.

- A researcher wishes to estimate the average weight of newborns in South America in the last five years. He takes a random sample of 235 newborns and obtains an average of 3.27 kilograms.
- What is the population of interest?
- What is the parameter of interest?
- Based on this sample, do we know the average weight of newborns in South America? Explain fully.

- A sociologist wishes to estimate the proportion of all adults in a certain region who have never married. In a random sample of 1,320 adults, 145 have never married, hence 145∕1320 ≈.11 or about 11% have never married.

- What is the population of interest?
- What is the parameter of interest?
- What is the statistic involved?
- Based on this sample, do we know the proportion of all adults who have never married? Explain fully.