Unit Test — Unit test Answers

Many large cities have considered or passed proposals that ban the use of plastic grocery bags in stores. A concerned student would like to measure if residents of her hometown would consider a similar ban on plastic bags. Standing in a busy shopping area, the student approaches adults and asks, "Items made of plastics are a dangerous, growing source of pollution to our world’s oceans and threaten many animal species. Given this, would you support a ban on plastic shopping bags in our city stores?” Which type of bias is most likely to be present in the survey results?

A trade school would like to measure the long-term success of their graduates after they leave the school. The school emails a survey requesting information from graduates about their work experience. One question asks graduates to share their annual salary, and the results of the question will be shared in a brochure for incoming students. Is it likely that the survey results will provide an accurate estimate of mean annual salary for all of the school’s graduates?

A trade school would like to measure the long-term success of its graduates after they leave the school, and emails a survey requesting information from graduates about their work experience. One question asks graduates if they are currently employed in the field they studied in school, while another asks them to share their annual salary. What type of bias is most likely to be present in the survey results?

An observational study of suburban towns reveals that towns with more dedicated park land tend to have higher median home prices. A real estate agent suggests that a town’s crime rate is a more accurate predictor of median home price.

A student would like to estimate the average number of text messages sent by cell-phone users in a day. Which of the following methods would provide a voluntary response sample?

A farmer sows 100 seeds of a new type of corn and wants to quickly determine the yield, or total number of ears of corn, for the crop when it has matured. He decides to take a simple random sample of the crop by using a random digit table. What is the fewest number of digits that should be used, given that there are 100 plants in total?

A tire company wants to determine if tires made with a new type of tread will last longer than tires made with the original type of tread. The company has access to 20 different vehicles and wants to use a randomized block design for the experiment.Which of the following variables would be the best to block the experimental units?

A doctor wants to determine if a new medication for cholesterol is more effective than the previous medication. The doctor asks her patients if they would like to take part in a study for a new medication, and 30 patients currently taking medication for cholesterol volunteer to participate. Which of the following would be an appropriate procedure for this experiment?

A community is considering raising funds to pay for improvements to the community swimming pool. To measure the level of interest, community leaders went door-to-door in a few neighborhoods and interviewed residents. Of the 230 residents contacted, 157 support raising funds to pay for improvements. Which of the following represents the sample in this setting?

What proportion of families own as opposed to rent their home? To find out, an urban planner selected a random sample of 400 families in a large city to participate in a survey about homeownership. Of the 362 families that responded to the survey, 42% reported that they own their home. Which of the following statements about the survey results is true?

A nutritionist would like to estimate the number of times adults exercise each week. To collect information, the nutritionist emails the members of the local fitness center. Which of the following describes the bias that may arise from the results?

Several members of a running club would like to survey the rest of the members to determine which 5K races the club should enter. They decide to use a random number table to sample 10 of the 78 members. Which of the following correctly labels the population?

Researchers would like to assess the overall health of white pine trees in a state park. Using a computer program, the researchers selected 100 random points in the state park and assessed the trees closest to the selected points. Of the 100 trees selected, 24 showed damage to their lower limbs. Which of the following describes the population in this setting?

A researcher is comparing the effectiveness of three devices designed to help people who snore. There are 60 people who snore participating in the experiment who are labeled 01–60. Using a table of random digits, the researcher will randomly place the participants into three equally sized treatment groups suitable for comparison. Carry out the random assignment using the given selection from a table of random digits, starting with the first row and first column.

A florist wants to determine if a new additive would extend the life of cut flowers longer than the original additive. The florist selects the first 20 carnations from the ones recently delivered by the greenhouse and assigns the first 10 to the new additive and the rest to the original additive. After three weeks, 6 carnations placed in the new additive still looked healthy, and 2 carnations placed in the original additive still looked healthy. The proportion of healthy carnations with the new additive was significantly greater than the proportion of healthy carnations with the original additive.