text book: Statistics: Concepts and Controversies.

complete 8 of the following:

Chapter 21: Exercise 21.10; page 505

Fire the coach? A college president says, "99% of the alumni support my firing of Coach Boggs." You contact an SRS of 200 of the college's 15,000 living alumni and find that 66 of them support firing the coach.

(a) What population does the inference concern here? (b) Explain clearly what the population proportion p is in this setting. (c) What is the numerical value of the sample proportion p^?

Chapter 21: Exercise 21.22; page 507

Harley motorcycles. In 2013, it was reported that 55% of the new motorcycles that were registered in the United States were Harley-Davidson motorcycles. You plan to interview an SRS of 600 new motorcycle owners.

(a) What is the sampling distribution of the proportion of your sample who own Harleys?

(b) How likely is your sample to contain 57% or more who own Harleys? How likely is it to contain at least 51% Harley owners? Use the 68-95- 99.7 rule and your answer to part (a).

Chapter 22: Exercise 22.16; page 529

Body temperature. We have all heard that 98.6 degrees Fahrenheit (or 37 degrees Celsius) is "normal body temperature." In fact, there is evidence that most people have a slightly lower body temperature. You plan to measure the body temperature of a random sample of people very accurately. You hope to show that a majority have temperatures lower than 98.6 degrees.

(a) Say clearly what the population proportion p stands for in this setting. (b) In terms of p, what are your null and alternative hypotheses?

Chapter 22: Exercise 22.24; page 531

Vote for the best face? Is the result of Exercise 22.21 statistically significant at the 5% level? At the 1% level?

Chapter 23: Exercise 23.12; pages 553

How far do rich parents take us? How much education children get is strongly associated with the wealth and social status of their parents. In social science jargon, this is "socioeconomic status," or SES. But the SES of parents has little influence on whether children who have graduated from college go on to yet more education. One study looked at whether college graduates took the graduate admissions tests for business, law, and other graduate programs. The effects of the parents' SES on taking the LSAT test for law school were "both statistically insignificant and small."

(a) What does "statistically insignificant" mean?

(b) Why is it important that the effects were small in size as well as insignificant?

Chapter 23: Exercise 23.20; page 554

What distinguishes those who have schizophrenia? Psychologists once measured 77 variables on a sample of people who had schizophrenia and a sample of people who did not have schizophrenia. They compared the two samples using 77 separate significance tests. Two of these tests were significant at the 5% level. Suppose that there is, in fact, no difference in any of the 77 variables between people who do and do not have schizophrenia in the adult population. That is, all 77 null hypotheses are true.

(a) What is the probability that one specific test shows a difference that is significant at the 5% level?

(b) Why is it not surprising that two of the 77 tests were significant at the 5% level?

Chapter 24: Exercise 24.22; page 579

Is astrology scientific? In Exercise 24.9, you described the relationship between belief that astrology is scientific and amount of higher education. Is the observed association between these variables statistically significant? To find out, proceed as follows.

(a) Add the row and column totals to the two-way table in Exercise 24.9 and find the expected cell counts. Which observed counts differ most from the expected counts?

(b) Find the chi-square statistic. Which cells contribute most to this statistic?

(c) What are the degrees of freedom? Use Table 24.1 to say how significant the chi-square test is. Write a brief conclusion for your study.

Chapter 24: Exercise 24.26; page 580

Standards for child care. Do unregulated providers of child care in their homes follow different health and safety practices in different cities? A study looked at people who regularly provided care for someone else's children in poor areas of three cities. The numbers who required medical releases from parents to allow medical care in an emergency were 42 of 73 providers in Newark, New Jersey, 29 of 101 in Camden, New Jersey, and 48 of 107 in South Chicago, Illinois.

(a) Use the chi-square test to see if there are significant differences among the proportions of child care providers who require medical releases in the three cities. What do you conclude?

(b) How should the data be produced in order for your test to be valid? (In fact, the samples came in part from asking parents who were subjects in another study who provided their child care. The author of the study wisely did not use a statistical test. He wrote: "Application of conventional statistical procedures appropriate for random samples may produce biased and misleading results.'')

Part IV Review: Exercise IV.2; page 583

Part IV Review: Exercise IV.14; page 586