Exam 5: Sampling: Surveys and How to Ask Questions

Use the following information for questions: According to a Gallup poll, about 90% of all American adults owned a cell phone at the time of the poll. The results are based on telephone interviews with a randomly selected national sample of 998 adults, 18 years and older. The margin of error was reported to be 3.5%. -What was the population of interest in this Gallup Poll?

Define the purpose of descriptive statistics.

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. -Questionnaires will be left on tables by the student union. When 1000 questionnaires are completed, the results will be reported.

Use the following information for questions: Decide if the sample is representative (or not) of the population for the question of interest. -What is the average age of people in Salt Lake City? Sample: 10 people picked randomly from all people living in Salt Lake City. Population: All people living in Salt Lake City.

If the target population is all U.S. adults, then a telephone directory would not make a good sampling frame because

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 1000 students with email addresses will be drawn from a list of all students with email addresses. Not every student has a campus email address.

Studies have shown that growing numbers of young girls are beginning to use steroids. At a committee hearing, a survey by the Centers for Disease Control and Prevention of high school students was cited, in which 7.3 percent of ninth-grade girls said they had used illegal steroids. One critic of the results objected to the methodology of the survey, which used an anonymous questionnaire and did not ask what substances were used. He suggested that some of the teenagers might have thought incorrectly that were using anabolic steroids. What type of bias is being raised by this issue?

Two polls were conducted to determine how much support there was for public funding of private schools. However, the results from the two polls were contradictory. One poll asked whether "students should attend private school at public expense". The other poll asked "How much do you support providing parents with the option of sending their children to the school of their choice - either public, private or parochial - rather than only to the school to which they are assigned?" Explain why the wording of the questions may have affected the results.

A librarian wants to gather data on the number of times books of fiction are checked out during the year. The library has 2000 books of fiction, of which 500 are murder mysteries, 400 are science fiction, and the rest are "other". She decides to sample 120 books. Suppose the librarian decides to take a simple random sample of 30 books from the murder mystery category, 24 from the science fiction category, and the remaining 66 from the other category. What sampling technique was used?

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 selects every 100^th student from a list of the 2000 students who took a foreign language that year, the sampling method is a

Use the following information for questions: A claim was made that at a local college only 5% of the students that take the introductory statistics course will continue their education in statistics. The Statistics Department at the college believes that this value is too low and decides to conduct a sample survey of 100 students that completed the introductory course the previous term. -Of the 100 selected students, 35 reported that they plan to continue an education in statistics. Report the results of this poll using the sample proportion and margin of error.

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 20 students are numbered from 01 to 20. Draw a simple random sample of 5 students by starting with the digit 01 from the first string of digits 00157. Which 5 students would be selected? (Do not use the more efficient method of, for instance, choosing number 1 if 21, 41, 61, or 81 is the random number.)

A random sample of 400 students involved in club activities showed that 250 were women. What is an approximate 95% confidence interval for the proportion of all students involved in club activities who are women?

Recently a group of adults who swim regularly for exercise was evaluated for depression. Each person's depression status was recorded as either currently depressed, likely to get depressed, or not depressed. It turned out that these swimmers were less likely to be depressed than the general population. What sample size was used if the margin of error was about 6%?

Use the following information for questions: The Michigan Department of State Police keeps track of the number of points received for various traffic violations by Michigan drivers. The department is interested in examining the relationship between the number of points received and the insurance premium. The following chart shows the number of drivers in each category of points according to the records from last year. The department will take a simple random sample of 3% of the drivers in the Low category and 2% of the drivers in the other two categories. -How many drivers will be included in the study?

Reword the following survey question so that it is less confusing. "Do you disagree with the policy of not allowing first year students parking permits on campus?"

Taxpayers in a population are listed in order of increasing income, with people with the lowest incomes listed first. A sample is selected by randomly choosing one of the first 100 names, then choosing every 100^th name from that point forward. This is an example of a __________ sample.

A population consists of 500 members and a simple random sample of 100 members is to be selected. Which of the following represents the most efficient method for labeling the members for selecting the sample using a random number table?

A national polling organization wishes to estimate the percentage of all teenagers who believe social security will 'be there' for them. The organization surveys a random sample of 1500 teenagers and 37% of this sample says that they believe social security will 'be there' for them. In this survey, what is the population of interest?

Use the following information for questions: First Avenue is in desperate need of repaving. The county road commission would like to survey the people who live along this road. They have a list available of all 176 household addresses along First Avenue with the addresses listed in numerical order by address. -Explain an efficient labeling scheme for taking a simple random sample of 20 household addresses.