Exam 6: Samples and Observational Studies

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 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

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

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 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?

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 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?

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 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?

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 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?

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?

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?

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?

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 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 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?

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?

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?

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?