For Exercise 2.1, see page 25; for Exercise 2.2, see page 30.
2.3 Biased sampling methods? A method for selecting a sample is said to be biased if
(a) the race or gender of respondents is taken into account.
(b) it systematically favors certain outcomes.
(c) the race or gender of the person asking the questions is known by respondents.
(d) any of the above is true.
2.4 An online survey. You go to a website to access a news story. In order to access the story, you are asked to answer a brief survey. If you choose not to answer the survey, you can only access the article for a fee.
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This method for obtaining a sample is an example of
(a) simple random sampling.
(b) random sampling, but not simple random sampling, because people visit the website at random.
(c) a convenience sample.
(d) a write-in opinion poll.
2.5 Simple random sample. I plan to take a sample of 10 students in my introductory statistics class. Which of the following is a simple random sample?
(a) I choose the 10 students sitting in the front row. Students select seats at random, so this would be a simple random sample.
(b) I choose the first 10 students who enter the classroom. Students arrive at random, so this would be a simple random sample.
(c) I write the names of all the students on similar slips of paper, put the slips of paper in a box, mix them well, and draw 10 slips from the box. The 10 names drawn are my sample.
(d) All of the above are simple random samples.
2.6 Random digits? Which of the following is true of a long string of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 produced by software that generates random digits or listed in a table of random digits?
(a) Any number in the string of digits is equally likely to be any of the 10 digits 0 through 9.
(b) Knowledge of the values in one part of the string of digits gives no information about the numbers in any other part.
(c) Any pair of digits in the string of digits is equally likely to be any of the 100 digits 00 through 99.
(d) All of the above are true.
2.7 Choosing a simple random sample. Angela, Juan, Kevin, Lucinda, and Tanya are students in my capstone course. I wish to select a simple random sample of two of them to work on a project. I label Angela as 1, Juan as 2, Kevin as 3, Lucinda as 4, and Tanya as 5. I generate the following sequence of four random digits using statistical software: 1, 7, 8, 4. Based on these digits, my simple random sample is
(a) Juan and Tanya.
(b) Angela and Lucinda.
(c) any pair of students because all are equally likely.
(d) impossible to determine. I need to generate additional digits.