ODD ANSWERS A45 21. Horizontal: Nominal; Vertical: Ratio 23. Horizontal: Nominal; Vertical: Ratio 25. (a) Interval (b) Nominal (c) Ratio (d) Ordinal 27. Qualitative. Ordinal. Data can be arranged in order, but the differences between data entries make no sense. 29. Qualitative. Nominal. No mathematical computations can be made and data are categorized by region. 31. Qualitative. Ordinal. Data can be arranged in order, but the differences between data entries are not meaningful. 33. An inherent zero is a zero that implies “none.” Answers will vary. Section 1.3 (page 24) 1. In an experiment, a treatment is applied to part of a population and responses are observed. In an observational study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions. 3. In a random sample, every member of the population has an equal chance of being selected. In a simple random sample, every possible sample of the same size has an equal chance of being selected. 5. False. A placebo is a fake treatment. 7. False. Using stratified sampling guarantees that members of each group within a population will be sampled. 9. False. A systematic sample is selected by ordering a population in some way and then selecting members of the population at regular intervals. 11. Experiment. The study applies a treatment (periods of wakeful rest or periods of distraction) to the subjects. 13. Observational study. The study does not apply a treatment to the adults. 15. Answers will vary. 17. Answers will vary. 19. (a) The experimental units are the 500 girls ages 13 to 17 who have acne. The treatment is the new cream used to treat acne. (b) Sample answer: A problem with the design is that the sample is not representative of the entire population because only girls ages 13 to 17 were used. To increase validity, use a stratified sample. (c) For the experiment to be double-blind, neither the subjects nor the company would know whether the subjects are receiving the acne cream or the placebo. 21. Sample answer: Treatment group: Jake, Arya, Nyla, Juan, Nia, Bruno, Kayla, Liam, and Kai. Control group: Xavier, Shaniece, Chen, Hana, Ansel, Liam, Mei, Zoey, and Sofia. A random number table was used. 23. Simple random sampling is used because each student has an equal chance of being contacted, and all samples of 300 students have an equal chance of being selected. A possible source of bias is that the random sample may contain a much greater percentage of students from one major than another. 25. Cluster sampling is used because the disaster area is divided into grids, and 30 grids are then entirely selected. A possible source of bias is that certain grids may have been much more severely damaged than others. 27. Stratified sampling is used because a sample is taken from each one-acre subplot. 29. Census, because it is relatively easy to obtain the GPAs of 85 students. 31. The question is biased because it already suggests that eating whole-grain foods improves your health. The question could be rewritten as “How does eating whole-grain foods affect your health?” 33. The survey question is unbiased. 35. Answers will vary. 37. Open Question Advantage: Allows respondent to express some depth and shades of meaning in the answer. Allows for new solutions to be introduced. Disadvantage: Not easily quantified and difficult to compare surveys. Closed Question Advantage: Easy to analyze results. Disadvantage: May not provide appropriate alternatives and may influence the opinion of the respondent. Section 1.3 Activity (page 27) 1. Answers will vary. The list contains one number at least twice. 2. The minimum is 1, the maximum is 731, and the number of samples is 8. Answers will vary. Uses and Abuses for Chapter 1 (page 28) 1. Answers will vary. 2. Answers will vary. Review Exercises for Chapter 1 (page 30) 1. Population: Collection of responses of all U.S. adults Sample: Collection of responses of the 1025 U.S. adults who were sampled Sample data set: Those sampled had visited the library an average of 10.5 times in the past 12 months. 3. Population: Collection of responses of all U.S. adults Sample: Collection of the responses of the 23,503 U.S. adults who were sampled Sample data set: 59% of adults who said if they were single, they would look up someone on the Internet before going on a date with them and 41% who would not 5. Population parameter. The value $4.8 billion is a numerical description of the amount of personal protective equipment imported. 7. Sample statistic. The value of 39% is a numerical description of a sample of U.S. workers. 9. The statement “59% said that if they were single, they would look up someone on the Internet before going on a date with them” is an example of descriptive statistics. An inference drawn from the sample is that a majority of adults would look someone up on the Internet before going on a date. 11. Quantitative, because ages are numerical measurements.
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