500 CHAPTER 9 Inferences from Two Samples that “money in a large denomination is less likely to be spent relative to an equivalent amount in smaller denominations.” Test that claim using a 0.05 significance level with the following sample data from the study. Group 1 Group 2 Subjects Given $1 Bill Subjects Given 4 Quarters Spent the money x1 = 12 x2 = 27 Subjects in group n1 = 46 n2 = 43 2. Denomination Effect Construct the confidence interval that could be used to test the claim in Exercise 1. What feature of the confidence interval leads to the same conclusion from Exercise 1? 3. Forecast and Actual Temperatures Listed below are actual temperatures 1°F2 along with the temperatures that were forecast five days earlier (data collected by the author). Use a 0.05 significance level to test the claim that differences between actual temperatures and temperatures forecast five days earlier are from a population with a mean of 0°F. Actual Temperature 1 °F2 80 77 81 85 73 73 80 72 83 81 Temperature 1 °F2 Forecast Five Days Earlier 80 80 79 80 79 82 76 73 77 83 4. Forecast and Actual Temperatures Construct the confidence interval that could be used to test the claim in Exercise 3. What feature of the confidence interval leads to the same conclusion from Exercise 3? Based on these results, does it appear that weather forecasters are doing a good job? 5. Smoking Cessation Programs Among 198 smokers who underwent a “sustained care” program, 51 were no longer smoking after six months. Among 199 smokers who underwent a “standard care” program, 30 were no longer smoking after six months (based on data from “Sustained Care Intervention and Postdischarge Smoking Cessation Among Hospitalized Adults,” by Rigotti et al., Journal of the American Medical Association, Vol. 312, No. 7). We want to use a 0.01 significance level to test the claim that the rate of success for smoking cessation is greater with the sustained care program. Test the claim using a hypothesis test. 6. Smoking Cessation Programs a. Construct the confidence interval that could be used to test the claim in Exercise 5. What feature of the confidence interval leads to the same conclusion from Exercise 5? b. Does the difference between the success rate of the sustained care program and the standard care program appear to have practical significance? c. Does the more successful program appear to have practical significance? 7. Seat Belts A study of seat belt use involved children who were hospitalized after motor vehicle crashes. For a group of 123 children who were wearing seat belts, the number of days in intensive care units (ICU) has a mean of 0.83 and a standard deviation of 1.77. For a group of 290 children who were not wearing seat belts, the number of days spent in ICUs has a mean of 1.39 and a standard deviation of 3.06 (based on data from “Morbidity Among Pediatric Motor Vehicle Crash Victims: The Effectiveness of Seat Belts,” by Osberg and Di Scala, American Journal of Public Health, Vol. 82, No. 3). Use a 0.05 significance level to test the claim that children wearing seat belts have a lower mean length of time in an ICU than the mean for children not wearing seat belts. 8. Seat Belts Construct the confidence interval that could be used to test the claim in Exercise 7. What feature of the confidence interval leads to the same conclusion from Exercise 7?
RkJQdWJsaXNoZXIy NjM5ODQ=