Sampling & Experimental Design Review

Why will it be impossible to conduct a double-blind experiment in the scenario described in question 1?

• The experimenter will know whether the child is a boy or a girl and whether he or she used flash cards or the computer.

• The child will know whether he or she is a boy or a girl.

• The child will know whether he or she used flash cards or the computer.

• The person who grades the tests will know whether the child was a boy or a girl.

• The person who grades the tests will know whether the child used flash cards or the computer.

Which of the following best describes the principal's sampling plan in question 2?

• A stratified random sample

• A simple random sample

• A cluster sample

• A convenience sample

• A systematic sample

Why is stratification used in the situation in question 3?

• To remove bias when estimating the proportion of working adults living in urban, suburban, and rural areas

• To remove bias when estimating the mean commuting time

• To reduce bias when estimating the mean commuting time

• To decrease the variability in estimates of the proportion of working adults living in urban, suburban, and rural areas

• To decrease the variability in estimates of the mean commuting time

What conclusion can be drawn from the study described in question 4?

• Cell phone use increases the likelihood of a car accident.

• There is an association between cell phone use and accidents, but not necessarily a causal relationship.

• There is a correlation between cell phone use and accidents, but not necessarily an association.

• The association between cell phone use and accidents is negative.

• Cell phone use causes more accidents in Canada, but not necessarily in the United States.

Which of the following should guide the formation of the blocks in question 5?

• Participants in the same block should receive the same lotion.

• Participants should be randomly assigned to the blocks.

• Participants should be kept blind as to which block they are in.

• Participants within each block should be as similar as possible with respect to how easily they get sunburned.

• Participants within each block should be as different as possible with respect to how easily they get sunburned.

Which of the following describes the sample and the population to which it would be most reasonable for the staff members to generalize the results?

• The sample is the 50 conference attendees, and the population is all teachers in the state.

• The sample is the 50 conference attendees, and the population is all conference attendees.

• The sample is all conference attendees, and the population is all teachers in the state.

• The sample is all conference attendees, and the population is the 50 conference attendees.

• The sample is the average number of years that all conference attendees have taught, and the population is all conference attendees.

What is one disadvantage to selecting a cluster sample to investigate the superintendent’s goal?

• Cluster sampling is usually very expensive to implement and could cost the district too much money.

• Because every senior in the selected clusters will complete the survey, the sample will be too large to yield accurate results.

• The schools in the cluster sample might not be representative of the population of seniors.

• There could be seniors absent from school on the day the survey is given, which could affect the results.

• There is no disadvantage to using a cluster sample.

Which of the following is potentially a confounding variable in this study?

• Chemical used

• Lab technician

• Dose

• Cell type

• Cell growth

Which of the following statements is true for problem 9?

• Each student leaving the cafeteria was randomly selected and could choose to answer or not, so there is no issue with the sampling method.

• Because students self-selected whether to eat in the cafeteria, the sampling method might be biased and the sample might not be representative of all students in the school.

• The survey would have been more effective if the reporter had collected the data in one 15-minute time period rather than in one 30-minute time period.

• The survey would have been more effective if students who cared about the food had called the reporter to tell how they felt about the new menu, so that only students with opinions on the subject would have been surveyed.

• Because no treatment was imposed on the students eating in the cafeteria, one cannot make any conclusions about the new menu.

Based on the design of the investigation in problem 10, which of the following is the largest population to which the results can be generalized?

• The 25 student athletes assigned to the beetroot juice group

• The 50 student athletes in the sample

• All student athletes at the college

• All students at the college

• All people who exercise