Stats ch 4

A random number generator is used to select 20 students from a class to rate a book. The 20 students selected are

• a voluntary response sample.

• a (simple random) sample of the class.

• highly biased.

• the population.

A school administrator uses a random number generator to select 20 students from the entire student body to participate in a survey about school lunches. The 20 students selected are:

• a voluntary response sample.

• a (simple random) sample of the student body.

• highly biased.

• the population.

Which one of the following is a valid statistical question?

• How many hours do you usually spend studying each week?

• What was the total attendance at the most recent football game?

• What is the current population of Canada?

• What is the distance between New York City and Los Angeles?

Which one of the following is a valid statistical question?

• How many hours do students typically spend on homework each night?

• What was the total attendance at the last school basketball game?

• How many people live in California?

• What is the average height of the Eiffel Tower in meters?

What is the purpose of the random assignment of treatments to subjects in an experiment?

• To produce bias in the selection of the subjects.

• To generalize to the population

• To show causation and create roughly equivalent groups.

• To eliminate the need for blinding in an experiment.

A fitness club owner wants to know how often members visit the gym each week. To gather data, she surveys the first 20 people who arrive at the gym on Monday morning. Which of the following statements is true?

• This is a voluntary response sample. It will likely overestimate the number of weekly visits, since people arriving early on Monday are likely more frequent gym-goers.

• This is a convenience sample. It will likely overestimate the number of weekly visits, since people arriving early on Monday are likely more frequent gym-goers.

• This is a convenience sample. It will likely underestimate the number of weekly visits, since people arriving early on Monday are likely more frequent gym-goers.

• This is a voluntary response sample. It will likely underestimate the number of weekly visits, since people arriving early on Monday are likely more frequent gym-goers.

A library manager wants to know how many books people typically borrow each month. To investigate, she surveys the first 20 people who enter the library on a Saturday morning. Which of the following statements is true?

• This is a convenience sample. It will likely overestimate the number of books borrowed, since people coming to the library early are likely avid readers.

• This is a voluntary response sample. It will likely overestimate the number of books borrowed, since people coming to the library early are likely avid readers.

• This is a convenience sample. It will likely underestimate the number of books borrowed, since people coming to the library early are likely avid readers.

• This is a voluntary response sample. It will likely underestimate the number of books borrowed, since people coming to the library early are likely avid readers.

A city council is debating whether to fund a new public park. One random survey asked residents, "Would you support investing in a new public park to improve community spaces?" and found 62% support. Another random survey asked, "Would you support spending taxpayer money on a new park?" and found only 45% support. Why are these results so different?

• These results most likely differ because of the difference in the wording that was used.

• These results most likely differ due to nonresponse bias.

• These results most likely differ just by chance due to random sampling.

• These results most likely differ due to undercoverage bias.

A school district is considering extending the school day by one hour. In one survey, parents were asked, "Do you support extending the school day to provide more learning opportunities?" and 57% responded "Yes." In another survey, parents were asked, "Do you support extending the school day, which would keep students at school for an extra hour?" and only 42% responded "Yes." Why are these results so different?

• These results most likely differ because of the difference in the wording that was used.

• These results most likely differ due to nonresponse bias.

• These results most likely differ just by chance due to random sampling.

• These results most likely differ due to undercoverage bias.

What is the main reason for using a control group when designing an experiment?

• to provide a baseline for comparing the effect of the treatment(s)

• to create roughly equivalent groups at the beginning of the experiment

• to increase sampling variability

• to generalize the results to a larger population