624 CHAPTER 12 Analysis of Variance 6. Does Candy Increase Restaurant Tips? A study was conducted to determine whether amounts of tips left for servers are affected by giving guests free candy along with the bill. Four different groups were used: (1) No candy, (2) one piece of candy, (3) two pieces of candy, (4) the offer of an additional piece of candy after the customer selected one piece of candy. The results of analysis of variance are shown in the accompanying TI-83>84 Plus display (based on data from “Sweetening the Till: The Use of Candy to Increase Restaurant Tipping,” by Strohmetz et al., Journal of Applied Social Psychology, Vol. 32, No. 2). Use a 0.05 significance level to test the claim that tip amounts are affected by giving guests candy. 7. Chocolate Chip Cookies Data Set 39 “Chocolate Chip Cookies” in Appendix B includes the counts of chocolate chips from the three different types of Chips Ahoy cookies. The accompanying StatCrunch display results from analysis of variance used with those three types of cookies. Use a 0.05 significance level to test the claim that the three different types of Chips Ahoy cookies have the same mean number of chocolate chips. 8. Secondhand Smoke Data Set 15 “Passive and Active Smoke” in Appendix B includes measured serum cotinine levels (mg>mL) from the three groups of subjects: 902 smokers, 433 nonsmokers exposed to tobacco smoke, and 358 nonsmokers not exposed to tobacco smoke. When nicotine is absorbed by the body, cotinine is produced. The results from analysis of variance are shown in the accompanying XLSTAT display. Use a 0.05 significance level to test the claim that the three samples are from populations with the same mean. What do the results suggest about the effects of secondhand smoke? 9. Clancy, Rowling, and Tolstoy Ease of Reading Pages were randomly selected from three books: The Bear and the Dragon by Tom Clancy, Harry Potter and the Sorcerer’s Stone by J.K. Rowling, and War and Peace by Leo Tolstoy. Listed below are Flesch Reading Ease Scores for those pages. Use a 0.05 significance level to test the claim that pages from books by those three authors have the same mean Flesch Reading Ease score. Given that higher scores correspond to text that is easier to read, which author appears to be different, and how is that author different? Clancy 58.2 73.4 73.1 64.4 72.7 89.2 43.9 76.3 76.4 78.9 69.4 72.9 Rowling 85.3 84.3 79.5 82.5 80.2 84.6 79.2 70.9 78.6 86.2 74.0 83.7 Tolstoy 69.4 64.2 71.4 71.6 68.5 51.9 72.2 74.4 52.8 58.4 65.4 73.6
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