Basic Definitions and Concepts
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.