help please
Adelaide (population of 1.3 million) is the hottest major city in Australia. An epidemiologist at the University of Adelaide did a case-control study of prevalent disease to measure the association between malignant melanoma (skin cancer) and various exposures. All exposures and disease were measured at one time point. Two 2x2 tables from this casecontrol study are shown below. _ melYanEma MEIaNZDma Tatals Vegetable- rich diet 40 Yes Vegetable-rich diet 75 160 No \" .0 Melanoma Melanoma Totals Yes No Regularly exercise outside 3 25 28 Yes Regularly exercise outside 173 No 200 1. Calculate the odds ratios for each of these two exposures: 2. With respect to prevalent melanoma, does the odds ratio suggest that people who eat a lot of vegetables have more melanoma, less melanoma, or is there no association? 3. With respect to prevalent melanoma, does the odds ratio suggest that people who regularly exercise outdoors have more melanoma, less melanoma, or is there no association? A second epidemiologist at the University of Adelaide did a 10-year observationai cohort study to measure the association between malignant melanoma (skin cancer) and various exposures. All participants were disease-free at the beginning of follow-up, and the epidemiologist measured several different exposures at the start of follow-up. Two ZxZ tables from this cohort study are shown below. Melanoma Melanoma Totals Yes No Vegetable-rich diet 3 1,497 1,500 Yes Vegetable-rich diet 8,483 8,500 10,000 Melanoma Melanoma Totals Yes No Regularly exercise outside 14 2,486 2,500 Yes Regularly exercise outside 7,494 7,500 No Totals 20 9,980 200 1. Calculate the risk ratios for each of these two exposures: 2. With respect to incident melanoma, does the risk ratio suggest that people who eat a lot of vegetables get more melanoma, less melanoma, or is there no association? 3. With respect to incident melanoma, does the risk ratio suggest that people who regularly exercise outdoors get more melanoma, less melanoma, or is there no association? 4. Study #BA examined prevalent melanoma whereas Study #33 examined incident melanoma. This is a key difference between studies. Compare the associations for vegetable-rich diet and regular outside exercise across these two studies. Why do you think the conclusions from these studies differed? [HINT: think about the issues of temporality and disease duration that can be a problem when studying prevalent disease]. 5. Although Study #BA and Study #38 were both valid studies, neither study design was optimal to investigate exposures that might cause malignant melanoma. The best study design would have been a case-control study of incident disease. Explain why this would have been the best design
