Deck 6: Samples and Observational Studies

Question 1

The owners of a health club are interested in finding out which of two brands of aerobic exercise equipment provides a more vigorous workout. They purchase 10 machines of each type and, for five days between 9 A.M. and 12 P.M., they measure the average pulse rate of each person who is working out on one of these 20 machines. This study is an example of

A)An experiment.
B)An observational study.
C)A paired data experiment.
D)A stratified experiment.

Answer 1

B

Question 2

A researcher is interested in opinions about stem cell research. A random sample of U.S. residents is selected, and the respondents are asked questions about stem cell research. The researcher then compares the responses of men and women in the sample. What is the best description of the overall sample?

A)Simple random sample
B)Stratified sample
C)Voluntary response sample
D)Experiment

Answer 2

A

Question 3

The city council in a suburb of Raleigh is interested in the level of public support for a tax increase to support restoration of nearby parks and waterways. A marketing research firm is hired that then selects a simple random sample of 50 adult residents and contacts each to determine whether the resident would be opposed to the tax increase. Of these respondents, 15 indicate that they would be opposed to the tax increase.
What is the sample in this example?

A)The 35 residents in favor of the increase
B)The 15 residents not in favor of the increase
C)The 50 residents selected
D)All residents in the suburb

Answer 3

C

Question 4

The city council in a suburb of Raleigh is interested in the level of public support for a tax increase to support restoration of nearby parks and waterways. A marketing research firm is hired that then selects a simple random sample of 50 adult residents and contacts each to determine whether the resident would be opposed to the tax increase. Of these respondents, 15 indicate that they would be opposed to the tax increase.
What is the chance that all 50 residents in a particular neighborhood end up being the sample of residents selected?

A)The population of the suburb divided by 50
B)The same as for any other set of 50 residents
C)Smaller than average due to the "cluster" effect
D)Smaller than average due to stratification

Question 5

The city council in a suburb of Raleigh is interested in the level of public support for a tax increase to support restoration of nearby parks and waterways. A marketing research firm is hired that then selects a simple random sample of 50 adult residents and contacts each to determine whether the resident would be opposed to the tax increase. Of these respondents, 15 indicate that they would be opposed to the tax increase.
What is the population of interest?

A)The residents in the suburb who are opposed to the tax increase
B)The 50 residents contacted
C)All adult residents in the suburb
D)All households in the suburb

Question 6

A student organization at a local college posted a poll on its website. After a semester, the results were tallied, and it was found that 95% of the respondents were in favor of raising fees to increase funding for student organizations. This conclusion was based on data collected from 5000 votes cast on the website. Which sampling technique is being used?

A)Simple random sampling
B)Stratified random sampling
C)Voluntary response sampling
D)Multistage sampling

Question 7

A student organization at a local college posted a poll on its website. After a semester, the results were tallied, and it was found that 95% of the respondents were in favor of raising fees to increase funding for student organizations. This conclusion was based on data collected from 5000 votes cast on the website. Based on the IP addresses of the respondents, it was later determined that 3200 of the votes were cast from a single off-campus computer belonging to a member of the student organization that posted the poll. What is the best description of the results of this poll?

A)They are reliable since there were still 1800 other randomly obtained respondents.
B)They are biased, but only slightly since the sample size was quite large.
C)They are biased, understating the popularity of raising fees.
D)They are biased, overstating the popularity of raising fees.

Question 8

If a researcher does not obtain complete information about a population, or leaves some segments of the population out, which bias may be present in the results?

A)Nonresponse bias
B)Response bias
C)Undercoverage bias
D)No bias

Question 9

A 2002 Gallup survey interviewed by phone a random sample of 474,195 U.S. adults. Participants were asked to describe their work status and to report their height and weight (to determine obesity based on a body mass index greater than 30). Gallup found 24.9% obese individuals among those interviewed who were employed (full-time or part-time by choice), compared with 28.6% obese individuals among those interviewed who were unemployed and looking for work.
What is the best description of the sample in this study?

A)Simple random sample
B)Stratified sample
C)Voluntary response sample
D)Cohort

Question 10

A 2012 Gallup survey interviewed by phone a random sample of 474,195 U.S. adults. Participants were asked to describe their work status and to report their height and weight (to determine obesity based on a body mass index greater than 30). Gallup found 24.9% obese individuals among those interviewed who were employed (full-time or part-time by choice), compared with 28.6% obese individuals among those interviewed who were unemployed and looking for work.
What is the population?

A)All U.S. adults
B)All U.S. adults who are obese
C)All U.S. adults who read Gallup surveys
D)The 474,195 U.S.adults interviewed

Question 11

A 2012 Gallup survey interviewed by phone a random sample of 474,195 U.S. adults. Participants were asked to describe their work status and to report their height and weight (to determine obesity based on a body mass index greater than 30). Gallup found 24.9% obese individuals among those interviewed who were employed (full-time or part-time by choice), compared with 28.6% obese individuals among those interviewed who were unemployed and looking for work.
What can you reasonably conclude from this survey?

A)The study used a voluntary response sample, so the results tell us nothing beyond what these participants answered.
B)The sample is too large for statistical significance.
C)Approximately 24.9% of American adults who are employed are obese compared with approximately 28.6% among those who are unemployed and looking for work.
D)Among American adults who read Gallup surveys, 24.9% of those who are employed are obese, compared with 28.6% of those who are unemployed and looking for work.

Question 12

The Study of Women's Health Across the Nation (SWAN) examines the physical and psychological changes affecting women during their middle-age years. The study began in 1994 and has since conducted annual interviews on a group of 3500 women near the menopausal transition. Which type of study is described?

A)A survey using a probability sample
B)A retrospective case-control study
C)A prospective cohort
D)Anecdotal evidence

Question 13

The National Health and Nutrition Examination Survey (NHANES) assesses the health and nutritional status of Americans. A recent NHANES asked a random sample of 17,567 American adults to fill out a detailed questionnaire about what they ate the previous day and give their body mass index (BMI). The researchers then compared individuals who ate avocado with those who didn't, and found that BMI was lower, on average, among those who ate avocado. This study is an example of

A)A survey using a probability sample.
B)A retrospective case-control study.
C)A prospective cohort.
D)Anecdotal evidence.

Question 14

A study of injuries to in-line skaters used data from the National Electronic Injury Surveillance System, which collects data from a random sample of hospital emergency rooms (ERs). The researchers interviewed 161 people who came to ERs with injuries from in-line skating. The interviews found that 53 people had been wearing wrist guards, and 6 of these people had wrist injuries. Of the 108 people who had not worn wrist guards, 45 had wrist injuries.
What is the population that was sampled in this survey?

A)The 161 individuals admitted to an ER for in-line skating injuries
B)All individuals admitted to an ER
C)All individuals admitted to an ER for wrist injuries
D)All in-line skaters admitted to an ER for skating injuries

Question 15

A study of injuries to in-line skaters used data from the National Electronic Injury Surveillance System, which collects data from a random sample of hospital emergency rooms (ERs). The researchers interviewed 161 people who came to ERs with injuries from in-line skating. The interviews found that 53 people had been wearing wrist guards, and 6 of these people had wrist injuries. Of the 108 people who had not worn wrist guards, 45 had wrist injuries.
What is the sample size?

A)161
B)108
C)53
D)51

Question 16

You need to select three subjects from a list of nine subjects:
1. Berliner   4. Wolfe   7. Verducci
2. Blumenthal   5. Stasny   8. Lin
3. MacEachern   6. Santner   9. Critchlow
Use the numerical labels attached to the names and the following list of random digits to select three individuals. Read the list of random digits from left to right, starting at the beginning of the list.
44982   20751   27498   12009   45287   71753   98236   66419   84533   11793   20495   05907   11384
The simple random sample is

A) 449.
B. 498.
C. Wolfe twice and Critchlow.
D)Wolfe, Critchlow, and Lin.

Question 17

You need to select three subjects from a list of nine subjects:
1. Berliner   4. Wolfe   7. Verducci
2. Blumenthal   5. Stasny   8. Lin
3. MacEachern   6. Santner   9. Critchlow
Use the numerical labels attached to the names and the following list of random digits to select three individuals. Read the list of random digits from left to right, starting at the beginning of the list.
44982   20751   27498   12009   45287   71753   98236   66419   84533   11793   20495   05907   11384
Which of the following statements is TRUE?

A) If we used another list of random digits to select the sample, we would get the same result as obtained with the list actually used.
B. If we used another list of random digits to select the sample, we would get a completely different sample than that obtained with the list actually used.
C. If we used another list of random digits to select the sample, we would get at most one name in common with a name obtained with the list actually used.
D)If we used another list of random digits to select the sample, the result obtained with the list actually used would be just as likely to be selected as any other set of three names.

Question 18

A total of 6972 homosexual and bisexual men enrolled in April 1984 have been participating in an ongoing study of HIV/AIDS. Participants are contacted twice a year to answer detailed lifestyle and medical questionnaires and provide a blood sample. This is an example of

A)A retrospective, case-control observational study.
B)A prospective, cohort observational study.
C)A sample survey.
D)A convenience sample.

Question 19

In 2001, the Department of Defense funded an ongoing study of current and former service members to evaluate the long-term health effects of military service, including deployments. Almost 150,000 participants have been recruited so far and have agreed to complete one questionnaire every three years. This is an example of

A)A retrospective, case-control observational study.
B)A prospective, cohort observational study.
C)A survey.
D)A convenience sample.

Question 20

Researchers at the National Cancer Institute queried men and women aged 50 and older about their diets, then followed participants for five years to record all diagnoses of head and neck cancer, which is the sixth-leading cause of cancer-related death worldwide. This is an example of

A)A retrospective, case-control observational study.
B)A prospective, cohort observational study.
C)A simple random survey.
D)A multistage sample survey.

Question 21

After becoming sick, a patient sees a doctor, who determines the most likely cause is an allergic reaction; the doctor prescribes an antihistamine. The patient returns home and stops burning candles and incense for the next week while taking the medication. By the end of the week, the patient is feeling better and is telling all his friends how wonderful the medication was at relieving his symptoms. What is the best description of this situation?

A)It is an example of convenience sampling since the patient stopped burning candles and incense only because it was easy.
B)It is an example of an experiment because the doctor prescribed the antihistamine to the patient, rather than letting the patient choose his medication.
C)It is an example of confounding, as there is no way to tell whether it was the medication that alleviated the patient's symptoms.
D)It is an example of bias because the patient wanted to feel better and would have reported relief of symptoms even if they had not improved.

Question 22

A study of the occupational exposure to HIV among health care workers recruited 33 health care workers who had become HIV-seropositive after exposure to HIV at work and 665 health care workers who had been exposed to HIV but had not become seropositive. The study found that contaminated health care workers were more likely to have been exposed to large amounts of blood and less likely to have taken the drug AZT immediately after exposure.
Which type of study is this?

A)Retrospective, case-control observational study
B)Prospective, cohort observational study
C)Sample survey
D)Anecdotal evidence

Question 23

A study of the occupational exposure to HIV among health care workers recruited 33 health care workers who had become HIV-seropositive after exposure to HIV at work and 665 health care workers who had been exposed to HIV but had not become seropositive. The study found that contaminated health care workers were more likely to have been exposed to large amounts of blood and less likely to have taken the drug AZT immediately after exposure than those who had not become seropositive.
What is the population in this study?

A)All health care workers who became HIV-seropositive after exposure to HIV at work
B)All health care workers who were exposed to HIV at work
C)All health care workers who are HIV-seropositive
D)Only the 698 health care workers interviewed

Question 24

Twiigs is an online polling website that allows users to easily create polls and to vote on polls created by other users. A March 2010 poll asked, "Has concern about autism influenced your decision about whether to vaccinate your child?" Of the 182 votes cast, 80% selected "No, I'm not worried about it."
Which type of sample was used in this poll?

A)Simple random sample
B)Stratified random sample
C)Multistage random sample
D)Voluntary response sample

Question 25

Twiigs is an online polling website that allows users to easily create polls and to vote on polls created by other users. A March 2010 poll asked, "Has concern about autism influenced your decision about whether to vaccinate your child?" Of the 182 votes cast, 80% selected "No, I'm not worried about it."
What can you conclude from this poll?

A)The great majority of parents are not influenced by concerns about autism when vaccinating their child.
B)The great majority of parents who visit Twiigs.com are not influenced by concerns about autism when vaccinating their child.
C)Nothing further because the sample is not random
D)Nothing further because the sample is too small

Question 26

A study enrolled 517 children aged 2 to 5 years with a diagnosis of autism spectrum disorder and 315 children of the same age group but without such a diagnosis. The mothers' medical records were examined to see whether they had a metabolic condition (e.g., diabetes, hypertension) during pregnancy. The researchers found that metabolic conditions during pregnancy tended to be more frequent among the mothers of children with autism spectrum disorder than among mothers of control children.
What can we reasonably conclude from this study?

A)Metabolic conditions during pregnancy cause autism.
B)Metabolic conditions during pregnancy are one cause of autism.
C)There is an association between metabolic conditions during pregnancy and autism.
D)There is no association between metabolic conditions during pregnancy and autism.

Question 27

Sixty-four pregnant women ranked the severity of their heartburn during pregnancy. Researchers rated newborn hair volume using photographs of the newborn's head. They found an association between heartburn severity during pregnancy and the amount of hair on newborns. What can we reasonably conclude from this study?

A)Eating food that causes heartburn during pregnancy leads to newborns who are hairier.
B)Newborn hair causes heartburn in pregnant women.
C)Pregnancy is confounded with heartburn in deciding the cause of newborn hair amount.
D)A lurking variable may influence both the severity of heartburn in pregnant women and the amount of hair on newborns; association does not imply causation.

Question 28

Early life corresponds to the first bacterial colonization of the digestive tract, creating a microbiome thought to play an important role in human development. What might be the effect of early exposure to antibiotics on children's development? One study followed 11,532 full-term babies all born in the county of Avon (United Kingdom) during 1991 and 1992. Exposures to antibiotics during infancy were recorded, along with measures of body mass at regular intervals over several years. The researchers found that antibiotic exposure during the first six months of life was associated with increased body mass later in childhood. What can we reasonably conclude from this study?

A)Early-life antibiotic exposure may lead to increased body mass in children.
B)Early-life antibiotic exposure leads to obesity.
C)Early-life antibiotic exposure causes children to gain more weight.
D)The microbiome regulates weight in children.

Question 29

On its website, the Washington Post dedicates a page to explaining its survey response rates. A September 2005 monthly political survey contacted 3246 American adults and got complete answers from 1201. What is the approximate 2005 response rate quoted by the Washington Post?

A)27%
B)37%
C)63%
D)73%

Question 30

On its website, the Washington Post dedicates a page to explaining its survey response rates. A September 2005 monthly political survey received complete responses from 1201 American adults, representing approximately a 37% response rate. How many individuals made up the original random sample selected by the Washington Post?

A)444
B)1906
C)3246
D)44,437

Question 31

A March 2010 SurveyUSA telephone poll on issues facing central Ohio contacted a random sample of 500 households in the Columbus, Ohio, area. One question was "Where 10 means most important, and 1 means least important, how important is protecting the environment?" The average response was 6.0.
Which population is the poll targeting?

A)All households in the Columbus area
B)All households with a strong opinion on the environment in the Columbus area
C)The 500 households in the Columbus area who responded
D)Registered voters in the Columbus area

Question 32

A March 2010 Survey USA telephone poll on issues facing central Ohio contacted a random sample of 500 households in the Columbus, Ohio, area. One question was "Where 10 means most important, and 1 means least important, how important is protecting the environment?" The average response was 6.0.
Which of the following is NOT a likely source of error in this survey?

A)Nonresponse
B)Question wording
C)Undercoverage from the need to have a telephone
D)Bias from a voluntary response sample

Question 33

Molecular evidence suggests a role for human papillomavirus (HPV) in the pathogenesis of oropharyngeal cancer. An epidemiologic study enrolled 100 hospitalized patients with newly diagnosed oropharyngeal cancer and 200 hospitalized patients without oropharyngeal cancer (controls). Oral HPV infection was strongly associated with oropharyngeal cancer, with 57 of the 100 patients with cancer having serologic evidence of HPV infection, compared with only 14 of the 200 patients without cancer.
Which type of study is this?

A)Epidemiologic survey using a probability sample
B)Retrospective, case-control study
C)Prospective, cohort study
D)Experiment using a convenience sample

Question 34

Molecular evidence suggests a role for human papillomavirus (HPV) in the pathogenesis of oropharyngeal cancer. An epidemiologic study enrolled 100 hospitalized patients with newly diagnosed oropharyngeal cancer and 200 hospitalized patients without oropharyngeal cancer (controls). Oral HPV infection was strongly associated with oropharyngeal cancer, with 57 of the 100 patients with cancer having serologic evidence of HPV infection compared with only 14 of the 200 patients without cancer.
What is the population represented by this study?

A)Hospitalized patients with or without oropharyngeal cancer
B)Hospitalized patients with an HPV infection
C)Hospitalized patients with oropharyngeal cancer and an HPV infection
D)The 300 patients studied