1. Which one of the following is a valid statistical question?

a. How many points did LeBron James score in the 2018 NBA playoffs?

b. When you call your cell-phone provider's customer service number, how long will you typically be on hold?

c. How tall is the Empire State Building?

d. How much money did Ivan's family spend on groceries last month?

2. A sportswriter wants to know how strongly Albuquerque residents support the local minor league baseball team, the Isotopes. She stands outside the stadium before a game and interviews the first 20 people who enter the stadium, asking them to rate their enthusiasm for the team on a 1 (lowest) to 5 (highest) scale.

Which of the following best describes the results of this survey?

a. This is a voluntary response sample and is likely to underestimate support for the team.

b. This is a convenience sample and is likely to overestimate the level of support for the team.

c. This is a random sample, but the size of the sample is too small to produce reliable results.

d. Because this is a random sample, there will be some sampling variability, but we can expect it to produce quite accurate results.

3. Some news organizations maintain a database of customers who have volunteered to share their opinions on a variety of issues. Suppose that one of these databases includes 9000 registered voters in California. To measure the amount of support for a controversial ballot issue, 1000 registered voters in California are randomly selected from the database and asked their opinion. Which of the following is the largest population to which the results of this survey should be generalized?

a. All registered voters in California

b. All California residents

c. The 1000 people in the sample

d. The 9000 registered voters from California in the database

4. A local news agency conducted a survey about unemployment by randomly dialing phone numbers until it had gathered responses from 1000 adults in the state. In the survey, 19% of those who responded said they were not currently employed. In reality, only 6% of the adults in the state were not currently employed at the time of the survey. Which of the following best explains the difference in the two percentages?

a. The difference is due to nonresponse. Adults who are employed are less likely to be available for the sample than adults who are unemployed.

b. The difference is due to response bias. Adults who are employed are likely to lie and say that they are unemployed.

c. The difference is due to undercoverage. The survey included only adults and did not include teenagers who are eligible to work.

d. The difference is due to sampling variability. We shouldn't expect the results of a random sample to match the truth about the population every time

5. A study of treatments for angina (pain due to low blood supply to the heart) compared bypass surgery, angioplasty, and use of drugs. The study looked at the medical records of thousands of angina patients whose doctors had chosen one of these treatments. It found that the average survival time of patients given drugs was the highest. Is it reasonable to conclude that using these drugs will prolong life for angina patients more than the other treatments will?

a. No, we can't conclude that these drugs prolong life because no placebo was used.

b. Yes, this study provides convincing evidence that these drugs prolong life and should be the treatment of choice.

c. No, we can't conclude that these drugs prolong life because the patients were volunteers.

d. No, we can't conclude that these drugs prolong life because the groups might differ in ways besides the treatment.

6. Some studies of the relationship between car color and frequency of accidents have found that red cars are more likely to be in accidents than black cars, despite how visible they are. Some experts warn that we should not conclude red cars are less safe than black cars because of possible confounding. Which of the following best describes what this means?

a. There are too many variables involved in traffic accidents to isolate the effect of car color.

b. It can be hard to determine if red cars or black cars are more visible on modern highways.

c. The accidents used in the study might not be a random sample of all accidents.

d. It is not possible to separate the effect of car color from the type of people who choose to drive red cars.

7. A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after taking the new remedy, 20 of the subjects reported that their headaches had disappeared. From this information, you conclude

a. nothing because there is no control group for comparison.

b. nothing because the sample size is too small.

c. that the remedy is effective for the treatment of headaches.

d. that the new treatment is better than aspirin.

8. Consider an experiment to investigate the effectiveness of different insecticides in controlling pests and their impact on the productivity of tomato plants. What is the best reason for randomly assigning treatments (spraying or not spraying) to the farms?

a. Random assignment eliminates chance variation in the responses.

b. Random assignment allows researchers to generalize conclusions about the effectiveness of the insecticides to all farms.

c. Random assignment will tend to balance out all other variables, such as soil fertility, so that they are not confounded with the treatment effects.

d. Random assignment eliminates the effects of other variables, like soil fertility.

9. Which of the following is not a benefit of keeping other variables the same in an experiment?

a. Keeping other variables the same eliminates the need for random assignment.

b. Keeping other variables the same makes it easier to get statistically significant results if one treatment is more effective than the other.

c. Keeping other variables the same reduces variability in the response variable.

d. Keeping other variables the same helps prevent confounding.

10. In the early 1960s, Stanley Milgram ran an experiment in which subjects were told they were "teachers" and were instructed to give electric shocks to other subjects ("students") when the latter made mistakes on a word-matching test. What the "teachers" didn't know was that the "students" were Milgram's assistants, who faked their discomfort at receiving non-existent shocks. Milgram showed that people were willing to administer what they thought were serious shocks rather than disobey someone in authority.

In what way did this experiment violate the principles of ethical research?

a. This experiment was unethical because Milgram did not include a control group of subjects who were told to not shock the students.

b. Due to the nature of the Milgram experiment, the sample size was likely not large enough.

c. This experiment violated the principle of blinding. Although the "students" knew they were not really getting shocked, the subjects didn't know that the students were not getting shocked.

d. It is unlikely that an institutional review board reviewed the Milgram experiment in advance. The review board would likely have rejected his experiment.