Chapter 1: Q8CQQ (page 1)
Observational Study or Experiment Are the data described in Exercise 6 the result of an observational study or an experiment?
The data described is an observational study.
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Statistical Significance and Practical Significance. In Exercises 13–16, determine whether the results appear to have statistical significance, and also determine whether the results appear to have practical significance.
IQ Scores Most people have IQ scores between 70 and 130. For $39.99, you can purchase a PC or Mac program from HighIQPro that is claimed to increase your IQ score by 10 to 20 points. The program claims to be “the only proven IQ increasing software in the brain training market,” but the author of your text could find no data supporting that claim, so let’s suppose that these results were obtained: In a study of 12 subjects using the program, the average increase in IQ score is 3 IQ points. There is a 25% chance of getting such results if the program has no effect.
In Exercises 29–36, answer the given questions, which are related to percentages.
Workplace Attire In a survey conducted by Opinion Research Corporation, 1000 adults were asked to identify “what is inappropriate in the workplace.” Of the 1000 subjects, 70% said that miniskirts were not appropriate in the workplace.
a. What is 70% of 1000?
b. Among the 1000 respondents, 550 said that shorts are unacceptable in the workplace. What percentage of respondents said that shorts are unacceptable in the workplace?
Statistical Significance and Practical Significance. In Exercises 13–16, determine whether the results appear to have statistical significance, and also determine whether the results appear to have practical significance.
Gender Selection In a study of the Gender Aide method of gender selection used to increase the likelihood of a baby being born a girl, 2000 users of the method gave birth to 980 boys and 1020 girls. There is about a 19% chance of getting that many girls if the method had no effect.
Question: Statistical Significance versus Practical Significance. When testing a new treatment, what is the difference between statistical significance and practical significance? Can a treatment have statistical significance but not practical significance?
In Exercises 17–20, refer to the sample of body temperatures (degrees Fahrenheit) in the table below. (The body temperatures are from a data set in Appendix B.)
Subject
| 1 | 2 | 3 | 4 | 5 | |
| 8 AM | 97 | 98.5 | 97.6 | 97.7 | 98.7 |
| 12 AM | 97.6 | 97.8 | 98 | 98.4 | 98.4 |
Context of the Data: Refer to the table of body temperatures. Is there some meaningful way in which each body temperature recorded at 8 AM is matched with the 12 AM temperature?
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