Checkpoint: Sampling 1

Question 1 Select one answer. 10 points

When conducting a survey, which of the following is themost importantreason to avoid using avolunteersample?

1. 1-In order to get stronger opinions expressed.
2. 2 -To ensure truthful answers to the survey's questions.
3. 3-Your conclusions could not be reliably generalized to a larger population.
4. 4 -You might not get a significant result.

Question 2 Select one answer. 10 points

Which of the following is an example of stratified sampling?

1. 1-A poll asked a random sample of 1,112 adults whether they believe that the use of marijuana for medical reasons should be legalized.
2. In order to assess students' satisfaction with the food establishment on campus, the first 50 students who came out of the student center were interviewed.
3. 2-A health educator wanted to study the sleeping habits of the undergraduate students in her university. For her study, the researcher chose a simple random sample of size 150 from each of the classes (150 freshmen, 150 sophomores, 150 juniors, and 150 seniors) for a total of 600 sampled students.
4. 3-A sample of 351 people called a radio show to express their opinions about the verdict in a murder trial.
5. 4-The human resources department of a large bank wanted to assess the job satisfaction of the bank's workers. The department chose four of the bank's branches at random and used all of the workers in those four branches as the subjects for the study.

Question 3 Select one answer. 10 points

The city council hired three college interns to measure public support for a large parks and recreation initiative in their city. The interns mailed surveys to 500 randomly selected participants in the current public recreation program. They received 150 responses.

Which of the following is the appropriate sampling frame in this scenario?

1. 1-The 150 people that responded
2. 2-The 500 people who got the survey
3. 3-All participants in the citys recreation program
4. 4-The participants that support the initiative
5. 5 -All members of the community

Question 4 Select one answer. 10 points

The city council hired three college interns to measure public support for a large parks and recreation initiative in their city. The interns mailed surveys to 500 randomly selected participants in the current public recreation program. They received 150 responses.

True or false? Even though the sample is random, it isnotrepresentative of the population of interest.

1. 1-True
2. 2-False

Question 5 Select one answer. 10 points

Talkshow host Bull Loney asked listeners of his to call in to give their opinion on a topic that he had just spent most of his program ranting about. The station got 384 calls.

This is an example of what type of sample?

1. 1-A voluntary response sample
2. 2-A multistage sample
3. 3-A simple random sample
4. 4-A convenience sample

Designing Studies Checkpoint 1 Question 6 Select one answer. 10 points

For their 1992 study, "The Effect of Country Music on Suicide" (published inSocial Forces, vol. 71, p. 211), researchers Stack and Gundlach investigated various American communities, recording the number of minutes of daily radio airtime devoted to country songs and the suicide rate. They found a moderately strong positive correlation.

In their paper, the researchers explain the results by saying that "the themes found in country musicfostera suicidal mood" (emphasis added). A news headline (The Independent[London], October 1, 2004, p. 15) about the research echoed these sentiments when it said, "Strange But True: Country Music Saps Will to Live." The research is even cited on various suicide-prevention websites, some with headings such as "Country Music Increases Suicide Risk."

Based on this study, can we have confidence in causality between country music and suicide?

1. 1- No, causality can be demonstrated only by investigating the entire population.
2. 2- Yes, as long as the communities were sampled randomly, and the number of communities (the sample size) was sufficiently large.
3. 3- Yes, causality is indicated by the moderately strong correlation.
4. 4- No, because the lack of assignment of communities to different levels of country music listening means there is a possibility of lurking variables.
5. 5- Yes, since different communities listened to different levels of country music, meaningful experimental comparisons can be made.

Question 7 Select all that apply. 10 points

Which of the following is an important advantage of experiments over observational studies? Check all that apply.

1. 1- Ensuring that each subject in the trial receives the best possible treatment
2. 2- Isolating the effects of a specific treatment
3. 3- Guaranteeing that approximately the same number of subjects is assigned to each treatment group
4. 4-Controlling for lurking variables to have a stronger case for causation

Question 8 Select one answer. 10 points

Which one of the following is an advantage of an observational study when compared to an experimental study?

1. 1- Lurking variables are not a problem.
2. 2- The treatment can be controlled by the researchers.
3. 3- Randomization is less important because researchers are observing things as they happen.
4. 4- The treatments studied may be unethical when used in experiments.

Question 9 Select one answer. 10 points

Suppose a study finds a positive correlation between the number of TV sets in the home of high school seniors and their admission rate into college. Which of the following might we conclude from this data?

1. 1- There may be a third variable that creates a link between the number of TVs in the home and college admission rate.
2. 2- Better students tend to have a TV set available.
3. 3-This is an anomaly and there is no relationship between TVs in the home and college admission rate.
4. 4- The increase in home TV sets improves the likelihood of college admission.

Question 10 Select all that apply. 10 points

Which of the following is an extremely important design element to have in an experimental study? Check all that apply.

1. 1- Treatments that are imposed by the experimenter
2. 2- A placebo
3. 3- Groups which are exactly the same size
4. 4-Randomized selection of participants

Question 11 Select all that apply. 10 points

In a study to determine the relationship between self esteem and eating, subjects had been randomly divided into two groups. One group of subjects were individually told something intended to boost their self esteem while in the other group subjects were individually told something intended to lower their self esteem. Each subject was then individually led into a room alone and asked to count the number of chocolate chip cookies in a very large container and told they could eat as many as they liked while conducting their count. Researchers then counted the number of cookies eaten by subjects in each group.

Which of the following statements is true regarding this study? Check all that apply.

1. 1- This study is an observational study.
2. 2- This study is blind.
3. 3- This study is an experimental study.
4. 4- The treatment was the number of cookies eaten.

Question 12 Select one answer. 10 points

In a recent study to establish the effectiveness of a new cancer drug, subjects were divided into three groups. Group A got a known and effective cancer drug, group B got the new experimental compound, and group C got a combination of the two drugs. In this study the nurses administering the drugs did not know which group or what drug was being administered to their patients. Which of the following is a correct statement about this study?

1. 1- It was not a blind study because there was no placebo.
2. 2-It was a double-blind study because neither the subject nor the experimenter knew what the treatment for a patient was.
3. 3-It was not a blind study because patients knew they were participating in a study.
4. 4- It was a blind study because subjects did not know the treatment they were receiving.

Question 13 Select one answer. 10 points

In a 2003 study by Bertrand and Mullainathan to measure racial discrimination in the labor market, experimenters sent fictitious resumes to help-wanted ads in Boston and Chicago newspapers. To manipulate perception of race each resume was assigned either a very African Americansounding name or a very White sounding name. They then measured the response to the resumes. Which of the following is a correct statement about this study?

Bertrand, M., and Mullainathan, S. Are Emily and Greg More Employable than Lakisha and Jamal? Working Paper 9873,National Bureau of Economic Research, 2003. http://www.nber.org/papers/w9873.pdf

1. 1- It was not a blind study because there was no placebo.
2. 2- It was problematic because the subjects didnt even know they were in an experiment.
3. 3-It was not a blind study because the experimenters knew where they were sending the resumes.
4. 4- It was a blind study because those who received the resumes did not know the treatment they received.