Unit Test — Unit test Answers

Research suggests that students could benefit from later school starting times. A school administrative team is considering a proposal to move the starting time of the local schools one hour later than the current start time. To measure interest in the proposal, members of the team randomly select subjects attending a large high school soccer tournament played on the high school grounds on a Saturday morning. The team finds that 58% of those surveyed support a later high school start time. Which type of bias is most likely to be present in the survey results?

A therapist wants to study the effects of yoga and meditation on stress relief. She has 60 volunteers who experience varying levels of stress. She believes that the volunteers’ professions could have an effect on the results. A preliminary survey reveals that 22 of the volunteers are in high-stress professions. The therapist randomly assigns 11 of these subjects to practice yoga and the remaining 11 to practice meditation. Nineteen of the other 38 volunteers are randomly assigned to practice yoga and the remaining 19 to practice meditation. Before the experiment begins, all the participants will be asked to rate their stress levels on a scale of 0 to 10, with 0 representing "no stress” and 10 representing "highest level of stress.” At the end of one month, the subjects will be asked to rate their stress levels again. The differences in stress levels will be compared for the different stress-relieving activities within the two types of professions.

A teacher assigns 10 questions for homework and wants to randomly pick 3 questions to be graded. Which of the following procedures would produce a simple random sample?

An automotive service center would like feedback on its customer service. Each customer receives a printed card after they pay for services with a short survey on which customer service is ranked on a scale from 1 (least satisfied) to 5 (most satisfied). Customers can then choose to submit the card in a box on their way out of the store. The store manager finds that 140 cards were filled out in the past week, with an average customer satisfaction score of 2.47. Which type of bias is most likely to be present in the survey results?

Some government leaders propose allowing oil companies to drill in currently protected lands that may be rich in oil reserves. Environmental researchers argue that drilling in such lands would be harmful to the surrounding ecosystem. To measure support for drilling in such lands, an oil company representative uses random-digit telephone dialing to contact adults in the region and measure opinion for increased drilling. One question in the survey asks, "Given that an increase in drilling could result in increased tax revenue and additional jobs to the region, would you support a proposal to allow drilling in lands currently protected from drilling?” What type of bias could be most likely affecting the survey results?