Exam 5: Sampling: Surveys and How to Ask Questions

For a survey of American diets a random sample of 1000 people were contacted. Of the 1000 people, 340 people completed the questionnaire. The results of this study, if applied to all Americans, are questionable because of

Use the following information for questions: These questions pertain to how to collect a random sample of 800 airline passengers from 100 particular flights leaving San Francisco International Airport. Assume there are 200 passengers aboard each flight. -Describe how to draw the sample as a stratified random sample, using the 100 flights as the strata.

The biggest problem with open questions is that the results can be difficult to summarize. If closed-form questions are preferred, explain how a pilot survey might be used to better formulate the closed-form questions.

A company has 500 employees and would like to select a simple random sample of 25 of them for a study. Of the following, only one fits the definition of a simple random sample. Which one is it?

Use the following information for questions: A poll is planned to determine what proportion of all students favor an increase in fees to support a new track and field stadium. For each study design, identify the main problem. -The questionnaire will be published in the student newspaper and the first 1000 completed questionnaires will be analyzed.

A professor wanted to find out whether students enrolled in her statistics class would like her to increase her office hours. She plans to take a random sample of 20 students among those coming to class on the next lecture day. Explain what the difficulty with her method is.

A random sample of Americans at least 65 years old showed that 32% believe their health is extremely important. If the sample size was 100, approximately what was the margin of error?

A weight-loss company is trying to promote its product. Based on a sample of 10 of their clients they model the relationship between starting weight and weight after 4 weeks using their product. It turns out that these 10 clients were selected because they had lost a decent amount of weight in 4 weeks. Clients who had lost hardly any weight or even gained weight were not included for this study. The results of this study, if applied to all clients, are questionable because of

A survey is planned to be done by contacting a random sample of people who have bought something over the Internet; the question would ask whether sales made over the Internet should be taxed or not. The purpose is to estimate the proportion of all Americans who would support an Internet sales tax. Explain why selection bias would be a problem for this survey.

A magazine printed a survey in its monthly issue and asked readers to fill it out and send it in. Over 1000 readers did so. This type of sample is called a

A census differs from a sample survey because

A student organization is trying to decide whether or not to offer more movies on campus. A random sample of students is about to be asked if they are in favor of more free movies on campus. What sample size would be needed to provide a margin of error of about 3%?

Sometimes questions are worded in such a way that the meaning is misinterpreted by a large percentage of the respondents. Which of the following types of bias would be most likely to be produced?

Use the following information for questions: A poll is planned to determine what proportion of all students favor an increase in fees to support a new track and field stadium. For each study design, identify the main problem. -A random sample of students will be called on the phone on Friday night and asked whether they favor a fee increase.

A Gallup poll reported that 88% of Americans say they have health insurance. If the sample size was 2500, an approximate 95% confidence interval for the proportion of all Americans who say they are insured is

In the College of Engineering exams aren't proctored. Students are required to write out the University honor code. They sign their name to pledge that they didn't cheat. But the engineering professors cannot observe if students cheat or not. One way to collect data on this topic would be to use an "exit poll": Have a Graduate Student Instructor ask the students if they cheated on the exam after the student has left the exam room. The results of this study, if applied to all students in the College of Engineering, are questionable because of

Use the following information for questions: The next question are based on the following row of digits from a random number table. Use these digits to select a random sample following steps 1 through 4 in the text. 00157 $\quad$ 37071 $\quad$ 79553 $\quad$ 31062 $\quad$ 42411 $\quad$ 79371 $\quad$ 25506 $\quad$ 69135 -Suppose that a group of 10 students are numbered from 0 to 9. Draw a simple random sample of 5 students by starting with the digit 1 in the first string of digits 00157. Which 5 students would be selected?

Which of the following would be most likely to produce response bias in a survey?

A Gallup poll reported that 58% of Americans say they are satisfied with the costs of healthcare. If the margin of error was 5%, approximately what was the sample size?

Use the following information for questions: Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. -If Olivia randomly selects 5 students from French, 5 from German, 5 from Spanish, and 5 from Chinese, the sampling method is a