2 from the report it isnt clear that the dog wasnt

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2. From the report it isn’t clear that the dog wasn’t just recognizing urine samples from people whose samples it had encountered before. 3. The researchers should make sure, if they didn’t already, that the urine samples used in the test were not from subjects whose urine the dog had previously encountered. Exercise 11-18 1. While prostate surgery may reduce your chances of dying of prostate cancer, it is not likely to prolong your life. (The figures are compatible with a large number of people in the surgery group dying on the operating table from their prostate surgery. That’s one way not to die of prostate cancer.) 2. This suggests that the surgery is not much of a cure for prostate cancer. 3. If this were the case, it might argue for the surgery. If the cohort is quite old when screened and diagnosed with prostate cancer, their chances of dying from some other cause before the prostate cancer can kill them are increased. If men are diagnosed at a younger age, the prostate cancer death rate may be higher. 4. This, for reasons similar to those given in the previous item, might argue against the surgery. Exercise 11-19 1.b 2. a 3. c or d. Item 4, below, is a better example of c. 4. c 5. b 6.d 7.e 8. e 9. b 10. a Exercise 11-20 1. a 2. a 3. c 4. c 5. b 6. a IM – 11 | 12
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7. a 8. b 9. b 10. a Exercise 11-21 1. a 2. c 3. b 4. a 5. b 6. b 7. c 8. a 9. c 10. a 11. b Exercise 11-22 ▲1. C; mowing the grass results in both fumes and grass dust. 2. B 3. A ▲4. C; shorter days contribute to both. 5. B 6. A ▲7. C; getting older can result in both conditions. 8. A, b and c all work for us. 9. B ▲10. B; maybe smarter people eat more fish. 11. B 12. C ▲13. B; if there is more violence, there is likely to be more on TV. 14. A or C 15. D ▲16. A 17. A 18. Maybe this is D. Maybe it is c (increased hours of sunlight is said to affect human moods; maybe it makes birds happy, too). ▲19. A; C is also possible since good health may have contributed both to Uncle Ted's attitude and to his longevity. 20. B IM – 11 | 13
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21. B ▲22. A; yes it could. 23. C 24. B ▲25. B; top executives can easily afford expensive clothes and nice cars. 26. C 27. B Exercise 11-23 The analysts attribute reduced productivity to marijuana use. However, causation could be in the reverse direction. Job loss may enhance substance abuse. Or it could be that, if marijuana use correlates negatively with productivity, it isn’t because marijuana itself impedes productivity. Some people may lose their jobs because they have been caught using marijuana, an illegal substance. In that case the loss of productivity wouldn’t be an effect of marijuana but an effect of marijuana’s prohibition. Exercise 11-24 The most plausible explanation is that there are more male drivers, or that males spend more time behind the wheel. IM – 11 | 14
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2 From the report it isnt clear that the dog wasnt just...

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