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1. Please turn off cell phones, pagers, etc. The lecture will begin shortly.

2. Lecture 28 This lecture will cover some questions similar to those you may find on Exam 3. This lecture will cover some questions similar to those you may find on Exam 3. In addition, there will be questions similar to the homework exercises.

3. In a survey of registered Democrats in New York State, participants were asked, “Will you support Hillary Clinton as a candidate for President in the 2008 Democratic primary election?” Responses are summarized in the table. Estimate the proportion of those who definitely intend to vote for Clinton among those who intend to vote in the primary. Freq Definitely yes 250 Definitely no 350 100 Maybe Won’t vote 300 Total 1000 A. 250 / 1000 B. 250 / 350 C. 250 / (250 + 350) D. 250 / (250 + 350 + 100) E. 250 / (350 + 100)

4. Patients being treated for schizophrenia were randomly assigned to receive a drug or a placebo. In the drug group, 67% showed substantial improvement. In the placebo group, 50% showed substantial improvement. The relative risk is .67 / .50 = 1.34. Which statement below is definitely correct? • Patients in the drug group were 17% more likely to show improvement than patients in the placebo group. • Patients in the drug group were 34% more likely to show improvement than patients in the placebo group. • We should not reject the null hypothesis. • The result is statistically significant but not practically significant. • The evidence against the null hypothesis is strong.

5. In the 2×2 table below, the odds ratio is • (120×60) / (50×144) = 1.0. Which statement is correct? 5-year survival Yes No Chemo 120 50 Radiation 144 60 A. There is no evidence against the null hypothesis. B. We should accept the null hypothesis. C. We should reject the null hypothesis. D. We should accept the alternative hypothesis. E. We should reject the alternative hypothesis.

6. County A had a higher crime rate than County B during • the 1980’s. County A also had a higher crime rate than County B during the 1990’s. But County B had a higher crime rate than County A for both decades combined. • This is A. impossible B. an example of Simpson’s paradox C. an example of a spurious relationship D. strong evidence against the null hypothesis E. an example of sampling error

7. Respondents in a national survey were classified by religiosity (highly religious, not highly religious) and whether they support the right of newspapers to print controversial cartoons depicting Mohammed (yes, no). The results were summarized in a 2×2 table. Which of the following is not a correct statement of the null hypothesis? • The relative risk in the population is 1.0. • The relative risk in the sample is close to 1.0. • Religiosity and opinion on this issue are unrelated. • The proportion of support among highly religious and non-highly religious people is the same. • The odds ratio in the population is 1.0.

8. Which of the following statements is not consistent • with the relative frequency interpretation of probability? • Upperclass students are more likely than first-year students to get A’s in Stat 100. • If a student is selected at random from this class, there’s an 80% chance that he or she will get an A on the next exam. • There’s an 80% chance that I will get an A on the next exam. • In State College, the chance of rain on a randomly selected day in April is about 20%. • Adults who drink alcohol in small quantities have a lower probability of heart disease than those who don’t drink at all.

9. Suppose the probability of a male birth is about .51 or 51%. A couple has two boys and is now expecting a third child. The probability that the next child will be a girl is A. 0.49 B. 0.51 × 0.51 × 0.49 C. 1 – (0.51 × 0.51 × 0.51) D. 0.49 × 0.49 × 0.51 E. 1 – (0.49 × 0.49 × 0.49)

10. The event “not A” is called the complement of A. • In other words, “A” and “not A” are complementary events. • Complementary events are A. mutually exclusive B. independent C. impossible D. rare E. subjective

11. You are a contestant on “Deal or No Deal.” There are • three briefcases left. One contains \$0, one contains \$6,000, and one contains \$300,000. Your briefcase is one of these, and the three amounts are equally likely. If you choose to open your briefcase, what is your expected prize? A. \$6,000 B. \$100,000 C. \$102,000 D. \$150,000 E. \$153,000

12. Laid off? Yes No Total African-American 130 1,382 1,512 White 87 2,813 2,900 Total 217 4,195 4,412 • Which of the following statements about this 2×2 table is correct? Note that (130/1512) / (87/2900) ≈ 2.9, and the p-value is 0.000. • African-Americans were about 2.9% more likely than Whites to be laid off. B. The odds ratio could be less than 1. C. The result is not statistically significant. D. African-Americans were about 3 times as likely as Whites to be laid off. E. The chisquare statistic could be about 2.5.