A46 ODD ANSWERS 13. Quantitative, because revenues are numerical measurements. 15. Interval.The data can be ordered and meaningful differences can be calculated but it does not make sense to say that 87 degrees is 1.09 times as hot as 80 degrees. 17. Nominal. The data are qualitative and cannot be arranged in a meaningful order. 19. Experiment. The study applied a treatment (medication used to reduce the risk of cardiac events) to the subjects. 21. Sample answer: The subjects could be split into male and female and then be randomly assigned to each of the five treatment groups. 23. Simple random sampling is used because random telephone numbers were generated and called. A potential source of bias is that telephone sampling only samples individuals who have telephones, who are available, and who are willing to respond. 25. Cluster sampling is used because each neighborhood is considered a cluster and every pregnant woman in a selected neighborhood is surveyed. A potential source of bias is that the selected neighborhoods may not be representative of the entire area. 27. Stratified sampling is used because the population is divided by grade level and then 25 students are randomly selected from each grade level. 29. Sampling, because the population of students at the university is too large for their favorite spring break destinations to be easily recorded. Random sampling would be advised because it would be easy to select students randomly and then record their favorite spring break destinations. Quiz for Chapter 1 (page 32) 1. Population: Collection of grade point averages, SAT scores, and ACT scores of all high school seniors. Sample: Collection of grade point averages, SAT scores, and ACT scores of 1622 high school seniors from four public high schools in the northeastern United States. 2. (a) Sample statistic. The value 42% is a numerical description of a sample of U.S. adults. (b) Population parameter. The 90% of members that approved the contract of the new president is a numerical description of all Board of Trustees members. (c) Sample statistic. The value 48% is a numerical description of a sample of small business owners. 3. (a) Qualitative, because debit card personal identification numbers are labels and it does not make sense to find differences between numbers. (b) Quantitative, because final scores are numerical measurements. 4. (a) Ordinal, because badge numbers can be ordered and often indicate seniority of service, but no meaningful mathematical computation can be performed. (b) Ratio, because one data entry can be expressed as a multiple of another. (c) Ordinal, because data can be arranged in order, but the differences between data entries make no sense. (d) Interval, because meaningful differences between entries can be calculated but a zero entry is not an inherent zero. 5. (a) Observational study. The study does not attempt to influence the responses of the subjects and there is no treatment. (b) Experiment. The study applies a treatment (video involving smoking) to the subjects. 6. Randomized block design 7. (a) Convenience sampling, because all of the people sampled are in one convenient location. (b) Systematic sampling, because every tenth machine part is sampled. (c) Stratified sampling, because the population is first stratified and then a sample is collected from each stratum. 8. Convenience sampling. People at campgrounds may be strongly against air pollution because they are at an outdoor location. Real Statistics—Real Decisions for Chapter 1 (page 34) 1. (a)–(b) Answers will vary. (c) Sample answer: Use surveys. (d) Sample answer: You may take too large a percentage of your sample from a subgroup of the population that is relatively small. 2. (a) Sample answer: Qualitative, because questions will ask for demographics and the sample questions have nonnumerical categories. (b) Sample answer: Nominal and ordinal, because the results can be put in categories and the categories can be ranked. (c) Sample (d) Statistics 3. (a) Sample answer: Sample includes only members of the population with access to the Internet. (b) Answers will vary. Chapter 2 Section 2.1 (page 49) 1. Organizing the data into a frequency distribution may make patterns within the data more evident. Sometimes it is easier to identify patterns of a data set by looking at a graph of the frequency distribution. 3. Class limits determine which numbers can belong to each class. Class boundaries are the numbers that separate classes without forming gaps between them. 5. The sum of the relative frequencies must be 1 or 100% because it is the sum of all portions or percentages of the data. 7. False. Class width is the difference between lower or upper limits of consecutive classes. 9. False. The graph of cumulative frequencies always starts at the lower boundary of the first class and increases to the upper boundary of the last class, therefore always increasing from left to right.
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