CHAPTER 3 EXERCISES

Question 3.90

3.90 Visit statistics and the news. STATS is an organization concerned about the appropriate reporting of statistical knowledge in the news media. Visit the website stats.org/blog. Some recent postings include discussions of deflategate, health claims for coffee, and the graph that launched a thousand news stories. Read one of the articles posted on this site and then write a short report summarizing the major ideas in the article.

Question 3.91

3.91 Online behavioral advertising. The Federal Trade Commission Staff Report, “Self-Regulatory Principles for Online Behavioral Advertising,” defines behavioral advertising as “the tracking of a consumer’s online activities over time—including the searches the consumer has conducted, the Web pages visited and the content viewed—in order to deliver advertising targeted to the individual consumer’s interests.” The report suggests four governing concepts for their proposals. These are (1) transparency and control: when companies collect information from consumers for advertising, they should tell consumers how the data will be collected, and consumers should be given a choice about whether to allow the data to be collected; (2) security and data retention: data should be kept secure and should be retained only as long as they are needed; (3) privacy: before data are used in a way that differs from promises made when they were collected, consent should be obtained from the consumer; and (4) sensitive data: affirmative express consent should be obtained before using any sensitive data.32 Write a report discussing your opinions concerning online behavioral advertising and the four governing concepts. Pay particular attention to issues related to the ethical collection and use of statistical data.

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Question 3.92

3.92 Confidentiality at NORC. The National Opinion Research Center conducts a large number of surveys and has established procedures for protecting the confidentiality of its survey participants. For its Survey of Consumer Finances, NORC provides a pledge to participants regarding confidentiality. This pledge is available at scf.norc.org/confidentiality.html. Review the pledge and summarize its key parts. Do you think that the pledge adequately addresses issues related to the ethical collection and use of data? Explain your answer.

Question 3.93

3.93 Make it an experiment! In the following observational studies, describe changes that could be made to the data collection process that would result in an experiment rather than an observational study. Also, offer suggestions about unseen biases or lurking variables that may be present in the studies as they are described here.

  1. (a) A friend of yours likes to play Texas hold ’em. Every time that he tells you about his playing, he says that he won.

  2. (b) In an introductory statistics class, you notice that the students who sit in the first two rows of seats had higher scores on the first exam than the other students in the class.

Question 3.94

3.94 Name the designs. What is the name for each of these study designs?

  1. (a) A study to compare two methods of preserving wood started with boards of southern white pine. Each board was ripped from end to end to form two edge-matched specimens. One was assigned to Method A; the other, to Method B.

  2. (b) A survey on youth and smoking contacted by telephone 300 smokers and 300 nonsmokers, all 14 to 22 years of age.

  3. (c) Does air pollution induce DNA mutations in mice? Starting with 40 male and 40 female mice, 20 of each sex were housed in a polluted industrial area downwind from a steel mill. The other 20 of each sex were housed at an unpolluted rural location 30 kilometers away.

Question 3.95

3.95 Price promotions and consumer expectations. A researcher studying the effect of price promotions on consumer expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Students in a marketing course view one or the other price history on a computer. Some students see a steady price, while others see regular promotions that temporarily cut the price. The students are then asked what price they would expect to pay for the detergent. Is this study an experiment? Why? What are the explanatory and response variables?

Question 3.96

3.96 Calcium and healthy bones. Adults need to eat foods or supplements that contain enough calcium to maintain healthy bones. Calcium intake is generally measured in milligrams per day (mg/d), and one measure of healthy bones is total body bone mineral density measured in grams per centimeter squared (TBBMD, g/cm2). Suppose that you want to study the relationship between calcium intake and TBBMD.

  1. (a) Design an observational study to study the relationship.

  2. (b) Design an experiment to study the relationship.

  3. (c) Compare the relative merits of your two designs. Which do you prefer? Give reasons for your answer.

Question 3.97

3.97 Choose the type of study. Give an example of a question about pets and their owners, their behavior, or their opinions that would best be answered by

  1. (a) a sample survey.

  2. (b) an observational study that is not a sample survey.

  3. (c) an experiment.

Question 3.98

3.98 Compare the fries. Do consumers prefer the fries from Burger King or from McDonald’s? Design a blind test in which the source of the fries is not identified. Describe briefly the design of a matched pairs experiment to investigate this question. How will you use randomization?

Question 3.99

3.99 Bicycle gears. How does the time it takes a bicycle rider to travel 100 meters depend on which gear is used and how steep the course is? It may be, for example, that higher gears are faster on level ground, but lower gears are faster on steep inclines. Discuss the design of a two-factor experiment to investigate this issue, using one bicycle with three gears and one rider. How will you use randomization?

Question 3.100

image 3.100 Design an experiment. The previous two exercises illustrate the use of statistically designed experiments to answer questions that arise in everyday life. Select a question of interest to you that an experiment might answer, and carefully discuss the design of an appropriate experiment.

Question 3.101

image 3.101 Design a survey. You want to investigate the attitudes of students at your school about the faculty’s commitment to teaching. The student government will pay the costs of contacting about 500 students.

  1. (a) Specify the exact population for your study; for example, will you include part-time students?

  2. (b) Describe your sample design. Will you use a stratified sample?

  3. (c) Briefly discuss the practical difficulties that you anticipate; for example, how will you contact the students in your sample?

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Question 3.102

3.102 Compare two doses of a drug. A drug manufacturer is studying how a new drug behaves in patients. Investigators compare two doses: 5 milligrams (mg) and 10 mg. The drug can be administered by injection, by a skin patch, or by intravenous drip. Concentration in the blood after 30 minutes (the response variable) may depend both on the dose and on the method of administration.

  1. (a) Make a sketch that describes the treatments formed by combining dose and method. Then use a diagram to outline a completely randomized design for this two-factor experiment.

  2. (b) “How many subjects?” is a tough issue. We will explain the basic ideas in Chapter 6. What can you say now about the advantage of using larger groups of subjects?

Question 3.103

3.103 Would the results be different for men and women? The drug that is the subject of the experiment in Exercise 3.102 may behave differently in men and women. How would you modify your experimental design to take this into account?

Question 3.104

image 3.104 Informed consent. The requirement that human subjects give their informed consent to participate in an experiment can greatly reduce the number of available subjects. For example, a study of new teaching methods asks the consent of parents for their children to be randomly assigned to be taught by either a new method or the standard method. Many parents do not return the forms, so their children must continue to be taught by the standard method. Why is it not correct to consider these children as part of the control group along with children who are randomly assigned to the standard method?

Question 3.105

image 3.105 Two ways to ask sensitive questions. Sample survey questions are usually read from a computer screen. In a Computer-aided personal interview (CAPI), the interviewer reads the questions and enters the responses. In a Computer-aided self interview (CASI), the interviewer stands aside and the respondent reads the questions and enters responses. One method almost always shows a higher percent of subjects admitting use of illegal drugs. Which method? Explain why.

Question 3.106

3.106 Your institutional review board. Your college or university has an institutional review board that screens all studies that use human subjects. Get a copy of the document that describes this board (you can probably find it online).

  1. (a) According to this document, what are the duties of the board?

  2. (b) How are members of the board chosen? How many members are not scientists? How many members are not employees of the college? Do these members have some special expertise, or are they simply members of the “general public”?

Question 3.107

3.107 Use of data produced by the government. Data produced by the government are often available free or at low cost to private users. For example, satellite weather data produced by the U.S. National Weather Service are available free to TV stations for their weather reports and to anyone on the Internet. Opinion 1: Government data should be available to everyone at minimal cost. Opinion 2: The satellites are expensive, and the TV stations are making a profit from their weather services, so they should share the cost. European governments, for example, charge TV stations for weather data. Which opinion do you support, and why?

Question 3.108

3.108 Should we ask for the consent of the parents? The Centers for Disease Control and Prevention, in a survey of teenagers, asked the subjects if they were sexually active. Those who said Yes were then asked, “How old were you when you had sexual intercourse for the first time?” Should consent of parents be required to ask minors about sex, drugs, and other such issues, or is consent of the minors themselves enough? Give reasons for your opinion.

Question 3.109

3.109 A theft experiment. Students sign up to be subjects in a psychology experiment. When they arrive, they are told that interviews are running late and are taken to a waiting room. The experimenters then stage a theft of a valuable object left in the waiting room. Some subjects are alone with the thief, and others are in pairs—these are the treatments being compared. Will the subject report the theft? The students had agreed to take part in an unspecified study, and the true nature of the experiment is explained to them afterward. Do you think this study is ethically OK?

Question 3.110

3.110 A cheating experiment. A psychologist conducts the following experiment. She measures the attitude of subjects toward cheating and then has them play a game rigged so that winning without cheating is impossible. The computer that organizes the game also records—unknown to the subjects—whether or not they cheat. Then attitude toward cheating is retested. Subjects who cheat tend to change their attitudes to find cheating more acceptable. Those who resist the temptation to cheat tend to condemn cheating more strongly on the second test of attitude. These results confirm the psychologist’s theory. This experiment tempts subjects to cheat. The subjects are led to believe that they can cheat secretly when, in fact, they are observed. Is this experiment ethically objectionable? Explain your position.