Solution: Percentages. answer the given questions, which are

Problem 1BSC Statistical Significance versus Practical Significance What is the difference between statistical significance and practical significance? Can a statistical study have statistical significance, but not practical significance?

Problem 3BSC Voluntary Response Sample What is a voluntary response sample, and why is such a sample generally not suitable for a statistical study?

Problem 4BSC Correlation and Causation What is meant by the statement that “correlation does not imply causation”?

Problem 2BSC Source of Data In conducting a statistical study, why is it important to consider the source of the data?

Problem 5BSC Consider the Source. determine whether the given source has the potential to create a bias in a statistical study. Physicians Committee for Responsible Medicine The Physicians Committee for Responsible Medicine tends to oppose the use of meat and dairy products in our diets, and that organization has received hundreds of thousands of dollars in funding from the Foundation to Support Animal Protection.

Problem 6BSC Consider the Source. ?determine whether the given source has the potential to create a bias in a statistical study. Body Measurements Data Set 1 in Appendix B includes body measurements obtained by the U.S. Department of Health and Human Services, National Center for Health Statistics.

Problem 7BSC Consider the Source. ?determine whether the given source has the potential to create a bias in a statistical study. Word Counts Data Set 17 in Appendix B includes word counts obtained by members of the Departments of Psychology at the University of Arizona, Washington University, and the University of Texas at Austin.

Problem 9 BSC Sampling Method. determine whether the sampling method appears to be sound or is flawed. Wi-Fi Security A survey of 721 subjects involved the providing of personal information when using Wi-Fi hotspots. The survey subjects were Internet users who responded to a question that was posted on the electronic edition of USA Today.

Problem 8 BSC Consider the Source. ?determine whether the given source has the potential to create a bias in a statistical study. Chocolate An article in ?Journal of Nutrition (Vol. 130, No. 8) noted that chocolate is rich in flavonoids. The article notes that “regular consumption of foods rich in flavonoids may reduce the risk of coronary heart disease.” The study received funding from Mars, Inc., the candy company, and the Chocolate Manufacturers Association.

Problem 10BSC Sampling Method. determine whether the sampling method appears to be sound or is flawed. Text Messaging In a survey of 109 subjects, each was asked to indicate how many text messages they send and receive each day. The sample consisted of those who chose to respond to the request posted on the StatCrunch Web site.

Problem 11BSC Sampling Method. determine whether the sampling method appears to be sound or is flawed. Applying for a Job In a survey of 514 human resource professionals, each was asked about the importance of the appearance of a job applicant. The survey subjects were randomly selected by Harris Interactive pollsters.

Problem 12BSC Sampling Method. determine whether the sampling method appears to be sound or is flawed. Evolution In a survey of beliefs about evolution, Gallup pollsters randomly selected and telephoned 1018 adults in the United States.

Problem 26BSC What’s Wrong? identify what is wrong. College Major In a USA Today online poll, 728 Internet users chose to respond, and 41% of them said that their college majors prepared them for their chosen careers very well.

Problem 27BSC What’s Wrong? identify what is wrong. Cell Phones and Pirates In recent years, the numbers of cell phones and the numbers of pirates have both increased, so there is a correlation, or association, between those two variables. Therefore, cell phones cause pirates.

Problem 28BSC What’s Wrong? identify what is wrong. Storks and Babies In the years following the end of World War II, it was found that there was a strong correlation, or association, between the number of human births and the stork population. It therefore follows that storks cause babies.

Problem 29BSC Percentages. answer the given questions, which are related to percentages. Evolution A Gallup poll of 1018 adults reported that 39% believe in evolution. a. What is the exact value that is 39% of 1018? b. Could the result from part (a) be the actual number of adults who said that they believe in evolution? Why or why not? c. What is the actual number of adults who said that they believe in evolution? d. Among the 1018 respondents, 255 said that they did not believe in evolution. What percentage of respondents said that they did not believe in evolution?

Problem 39 BSC What's Wrong with This Picture? The Newport Chronicle ran a survey by asking readers to call in.their response to this question: “Do you support the development of atomic weapons that could kill millions of innocent people?” It was reported that 20 readers responded and that 87% said “no,” while 13% said “yes.” Identify four major flaws in this survey.

Problem 13BSC Statistical Significance and Practical Significance. ?determine whether the results appear to have statistical significance, and also determine whether the results have practical significance. Waite Diet? In a study of the Marisa Waite diet, four subjects lost an average of 45 pounds. It is found that there is about a 30% chance of getting such results with a diet that has no effect.

Problem 14BSC Statistical Significance and Practical Significance. ?determine whether the results appear to have statistical significance, and also determine whether the results have practical significance. Gender Selection? In a study of the Gender Aide method of gender selection, 1000 users of the method gave birth to 540 boys and 460 girls. There is about a 1% chance that such extreme results would occur if the method had no effect.

Problem 16BSC Statistical Significance and Practical Significance. determine whether the results appear to have statistical significance, and also determine whether the results have practical significance. IQ Scores Most people have IQ scores between 70 and 130. For $32, you can purchase a computer program from Highiqpro.com 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;.

Problem 15BSC Statistical Significance and Practical Significance. determine whether the results appear to have statistical significance, and also determine whether the results have practical significance. Guessing Technique When making random guesses for difficult multiple-choice test questions with possible answers of a, b, c, d, and e, we expect to get about 20% of the answers correct. The Ashton Prep Program claims to have developed a better method of guessing. In a test of that program, guesses were made for 100 answers, and 23 were found to be correct. There is a 23% chance of getting such results if the program has no effect.

Testing Claims About Proportions. In Exercises 7–18, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-­value or critical value(s), conclusion about the null hypothesis, and final conclusion that addresses the original claim. Lefties In a random sample of males, it was found that 23 write with their left hands and 217 do not. In a random sample of females, it was found that 65 write with their left hands and 455 do not (based on data from “The Left­-Handed: Their Sinister History,” by Elaine Fowler Costas, Education Resources Information Center, Paper 399519). We want to use a 0.01 significance level to test the claim that the rate of left-­handedness among males is less than that among females. a. Test the claim using a hypothesis test. b. Test the claim by constructing an appropriate confidence interval. c. Based on the results, is the rate of left­-handedness among males less than the rate of left­-handedness among females?

Testing Claims About Proportions. In Exercises 7–18, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-­value or critical value(s), conclusion about the null hypothesis, and final conclusion that addresses the original claim. Marathon Finishers In a recent New York City marathon, 25,221 men finished and 253 dropped out. Also, 12,883 women finished and 163 dropped out (based on data from the New York Times). We want to use a 0.01 significance level to test the claim that the rate of those who finish is the same for men and women. a. Test the claim using a hypothesis test. b. Test the claim by constructing an appropriate confidence interval. c. Based on the results, do men and women finish the New York City marathon at the same rate?

In Exercises 17–20, refer to the data in the table below. (The pulse rates are from one sample of randomly selected males and a different sample of randomly selected females listed in Data Set 1 in Appendix B.) Conclusion Given the data in the table, what issue can be addressed by conducting a statistical analysis of the pulse rates?

In Exercises 21–24, refer to the data in the table below. The IQ score and brain volume are listed for each of five different subjects. (The values are from Data Set 6 in Appendix B.) Context of the Data Refer to the given table of measurements. Is there some meaningful way in which the IQ scores are matched with the corresponding brain volumes? If they are matched, does it make sense to use the difference between each IQ score and the brain volume that is in the same column? Why or why not?

In Exercises 17–20, refer to the data in the table below. (The pulse rates are from one sample of randomly selected males and a different sample of randomly selected females listed in Data Set 1 in Appendix B.) Conclusion If we use the listed pulse rates with suitable methods of statistics, we conclude that when the 64.0 average (mean) of the pulse rates of the five males is compared to the 69.6 average (mean) of the pulse rates of the five females, there is a 36% chance that the difference can be explained by random results obtained from populations of males and females having the same average (mean) pulse rate. Does this prove that the populations of males and females have the same average (mean) pulse rate? Why or why not? Would better results be obtained with larger samples?

In Exercises 21–24, refer to the data in the table below. The IQ score and brain volume are listed for each of five different subjects. (The values are from Data Set 6 in Appendix B.) Source of the Data The data in the table were obtained by members of departments at Harvard Medical School, Massachusetts General Hospital, Dartmouth College, Dartmouth Medical School, and the University of California at Davis. Funding for the study was provided by awards from the National Institutes of Health, which is an agency of the U.S. Department of Health and Human Services. Does the source of the data appear to be unbiased?

In Exercises 21–24, refer to the data in the table below. The IQ score and brain volume are listed for each of five different subjects. (The values are from Data Set 6 in Appendix B.) Conclusion Given the context of the data in the table, what issue can be addressed by conducting a statistical analysis of the measurements?

In Exercises 21–24, refer to the data in the table below. The IQ score and brain volume are listed for each of five different subjects. (The values are from Data Set 6 in Appendix B.) Conclusion If we were to use such data and conclude that there is a correlation or association between IQ score and brain volume, does it follow that larger brains are the cause of higher IQ scores?

Problem 25BSC What’s Wrong? i ? dentify what is wrong. Potatoes? In a poll sponsored by the Idaho Potato Commission, 1000 adults were asked to select their favorite vegetables, and the favorite choice was potatoes, which were selected by 26% of the respondents.

Problem 32 BSC Percentages. answer the given questions, which are related to percentages. Dollar for Your Thoughts In a Harris poll of 2513 adults, 76% said that they prefer $1 to be in the form of paper currency. a. What is the exact value that is 76% of 2513? b. Could the result from part (a) be the actual number of adults who said that they prefer $ 1 to be in the form of paper currency? Why or why not? c. What is the actual number of adults who said that they prefer $1 to be in the form of paper currency? d. Among the 2513 respondents, 327 said that they prefer $1 to be currency in the form of a coin. What is the percentage of respondents who said that they prefer $ 1 to be currency in the form of a coin?

Problem 31BSC Percentages. answer the given questions, which are related to percentages. Piercings and Tattoos In a Harris poll of 2302 adults, 14% said that they have a tattoo. a. What is the exact value that is 14% of 2302? b. Could the result from part (a) be actual number of adults who said that they have a tattoo? Why or why not? c. What is the actual number of adults who said that they have a tattoo? d. Among the 2302 respondents, 46 said that they had face piercings only. What percentage of respondents had face piercings only?

Problem 33BSC Percentages. answer the given questions, which are related to percentages. Percentages in Advertising An ad for Big Skinny wallets included the statement that one of their wallets “reduces your filled wallet size by 50%—200%.” What is wrong with this statement?

Problem 30BSC Percentages. ?answer the given questions, which are related to percentages. Online Shopping? In a ?Consumer Reports? Research Center Telephone survey of 427 women, 38% said that they purchased clothing online. a.? What is the exact value that is 38% of 427? b.? Could the result from part (a) be the actual number of women who said that they purchase clothing online? Why or why not? c.? What is the actual number of women who said that they purchase clothing online? d.? Among the 427 respondents, 30 said that they purchase electronics online. What percentage of the women said that they purchase electronics online?

Problem 37BSC ATV Accidents? The Associated Press provided an article with a headline stating that ATV accidents killed 704 people in the last year. The article noted that this is a new record high and compares it to 617 ATV deaths the year before that. Other data about the frequencies of injuries were included. What important value was not included? Why is it important?

Problem 36BSC Percentages. ?answer the given questions, which are related to percentages. Percentages in Advertising? A ?New Yo?rk Times editorial criticized a chart caption that described a dental rinse as one that “reduces plaque on teeth by over 300%.” What is wrong with this statement?

Problem 35BSC Percentages. ?answer the given questions, which are related to percentages. Percentages in the Media? In the ?New York Times M ? agazine, a report about the decline of Western investment in Kenya included this statement: “After years of daily flights, Lufthansa and Air France had halted passenger service. Foreign investment fell 500 percent during the 1990s.” What is wrong with this statement?

Problem 38BSC Falsifying Data A researcher at the Sloan-Kettering Cancer Research Center was once criticized for falsifying data. Among his data were figures obtained from 6 groups of mice, with 20 individual mice in each group. The following values were given for the percentage of successes in each group: 53%, 58%, 63%, 46%, 48%, 67%. What’s wrong with those values?

Problem 34BSC Percentages. ?answer the given questions, which are related to percentages. Percentages in Advertising? In an ad for the Club, a device used to discourage car thefts, it was stated that “The Club reduces your odds of car theft by 400%.” What is wrong with this statement?

Problem 8 BSC Consider the Source. determine whether the given source has the potential to create a bias in a statistical study. Chocolate An article in Journal of Nutrition (Vol. 130, No. 8) noted that chocolate is rich in flavonoids. The article notes that “regular consumption of foods rich in flavonoids may reduce the risk of coronary heart disease.” The study received funding from Mars, Inc., the candy company, and the Chocolate Manufacturers Association.