Question 1 of 12 The authors of a cross-sectional study hypothesized that lack of regular exercise is associated with obesity in children. Their study of 12 children in Michigan, however, failed to show a statistically significant association between exercise habits and obesity (OR = 1.9, p = 0.11). Selection Bias Confounding Information Bias Random Error Question 2 of 12 Please provide a rationale for your choice in question 1. Maximum number of characters (including HTML tags added by text editor): 32,000 Question 3 of 12 Please indicate the probable direction of the bias (if applicable) to your choice for question 1 A. negative B. positive C. N/A Question 4 of 12 0.25 Points In a case-control study of the relationship between intravenous drug use and HIV infection, the investigators discovered after the study that the case group had tended to underreport their drug use due to fears arising from previous convictions for drug-related violations. Underreporting was not a problem in the control group, however, which was not under medical supervision at the time. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 5 of 12 Please provide a rationale for your choice in question 4. (500 words) Question 6 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 4. A. negative B. positive C. N/A Question 7 of 12 A prospective cohort study followed 8,542 women for 10 years to determine if alcohol consumption increased the risk of breast cancer. No statistically significant association was found. Twelve thousand women had been enrolled in the study at its initiation, but 3,458 had withdrawn during the 10-year period. A follow-up of spouses, friends, and relatives of the women who withdrew revealed that more than 60% of the withdrawals had developed breast cancer and that nearly 84% were regular drinkers. A. Selection Bias B. Confounding C. Information Bias D. Random Error PART A: Each of the following problems contains a potential error that could affect the accuracy of the results. a. Using the key below, indicate the most likely source of error in each problem based solely on the information provided. b. Provide a rationale for your answers, including an explanation of how the selection or information bias, confounding, or random error, as appropriate, could have biased the observed results. c. If A, B, or C is selected, indicate the likely direction of the bias or confounding (e.g., toward or away from the null value). Question 1 of 12 0.25 Points The authors of a cross-sectional study hypothesized that lack of regular exercise is associated with obesity in children. Their study of 12 children in Michigan, however, failed to show a statistically significant association between exercise habits and obesity (OR = 1.9, p = 0.11). A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 2 of 12 0.25 Points Please provide a rationale for your choice in question 1. Maximum number of characters (including HTML tags added by text editor): 32,000 Show/Hide Rich-Text Editor Question 3 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 1 A. negative B. positive C. N/A Question 4 of 12 0.25 Points In a case-control study of the relationship between intravenous drug use and HIV infection, the investigators discovered after the study that the case group had tended to underreport their drug use due to fears arising from previous convictions for drug-related violations. Underreporting was not a problem in the control group, however, which was not under medical supervision at the time. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 5 of 12 0.25 Points Please provide a rationale for your choice in question 4. (500 words) Question 6 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 4. A. negative B. positive C. N/A Question 7 of 12 0.25 Points A prospective cohort study followed 8,542 women for 10 years to determine if alcohol consumption increased the risk of breast cancer. No statistically significant association was found. Twelve thousand women had been enrolled in the study at its initiation, but 3,458 had withdrawn during the 10-year period. A follow-up of spouses, friends, and relatives of the women who withdrew revealed that more than 60% of the withdrawals had developed breast cancer and that nearly 84% were regular drinkers. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 8 of 12 0.25 Points Please provide a rationale for your choice in question 7. (500 words) Question 9 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 7. A. negative B. positive C. N/A Question 10 of 12 0.25 Points A large epidemiologic study found that elderly adults with dementia were more likely to develop liver cancer than those without dementia. The investigators, however, could offer no plausible biological mechanism for the association between dementia and liver cancer. Many of the subjects reported heavy drinking, however. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 11 of 12 0.25 Points Please provide a rationale for your choice in question 10. (500 words) Question 12 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 4. A. negative B. positive C. N/A a) What kind of misclassification is this? b) Calculate the odds ratio and determine the direction of the bias, if any. Part 2 of 3 - PART B The tables below represent data from a case control study of a bone density and its association with hip fracture. The data have been stratified by age as follows: Age >=80 Hip Fracture No hip fracture Low bone density 72 20 High bone density 18 20 90 40 Age 65-79 Hip Fracture No hip fracture Low bone density 5 32 High bone density 5 128 10 160 Question 1 of 3 0.5 Points (a) Calculate the appropriate crude and stratum specific measures of association for this study. (b) Based on your calculations, does age confound the observed bone density - hip fracture association? (c) If so, in what direction? Question 2 of 3 0.5 Points Consider a case-control study of red meat consumption and prostate cancer. There are 350 cases of prostate cancer and 350 controls. 200 cases and 131 controls are known to have been regular consumers of red meat. Create the appropriate 2x2 table and calculate the odds ratio. Question 3 of 3 0.5 Points Now, assume that 10% of the true 'red meat consumers' users were misclassified as non-consumers and 10% of the actual non-consumers were misclassified as red meat consumers among both the cases and controls. a) What kind of misclassification is this? b) Calculate the odds ratio and determine the direction of the bias, if any. Part 3 of 3 - PART C Please read the following two articles before answering the questions noted below. Bruneau J, Lamothe F, et al. High rates of HIV infection among IDU participating in needle exchange programs in Montreal: results from a cohort study. American Journal of Epidemiology. 1997;146:994-1002. Lurie P. Invited commentary: le mystere de Montreal. American Journal of Epidemiology. 1997; 146: 1003-1006. Question 1 of 5 0.5 Points This paper provides results from several different study designs. Please briefly describe what these study designs were. (500 words) Question 3 of 5 0.5 Points What confounders were considered in this study? How did the investigators determine if these confounders were associated with the exposure of interest (NEP use)? (500 words) Question 4 of 5 0.5 Points What were the overall results of the study? What possible explanations were provided to explain these results? (500 words) Question 5 of 5 0.5 Points Read Peter Lurie's accompanying comment on this study. If you were a policymaker, how would the results of this study (in the context of Lurie's comments) influence your decision about whether to implement NEP in your community? (500 words) Question 1 of 12 The authors of a cross-sectional study hypothesized that lack of regular exercise is associated with obesity in children. Their study of 12 children in Michigan, however, failed to show a statistically significant association between exercise habits and obesity (OR = 1.9, p = 0.11). Selection Bias Confounding Information Bias Random Error Question 2 of 12 Please provide a rationale for your choice in question 1. Maximum number of characters (including HTML tags added by text editor): 32,000 Question 3 of 12 Please indicate the probable direction of the bias (if applicable) to your choice for question 1 A. negative B. positive C. N/A Question 4 of 12 0.25 Points In a case-control study of the relationship between intravenous drug use and HIV infection, the investigators discovered after the study that the case group had tended to underreport their drug use due to fears arising from previous convictions for drug-related violations. Underreporting was not a problem in the control group, however, which was not under medical supervision at the time. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 5 of 12 Please provide a rationale for your choice in question 4. (500 words) Question 6 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 4. A. negative B. positive C. N/A Question 7 of 12 A prospective cohort study followed 8,542 women for 10 years to determine if alcohol consumption increased the risk of breast cancer. No statistically significant association was found. Twelve thousand women had been enrolled in the study at its initiation, but 3,458 had withdrawn during the 10-year period. A follow-up of spouses, friends, and relatives of the women who withdrew revealed that more than 60% of the withdrawals had developed breast cancer and that nearly 84% were regular drinkers. A. Selection Bias B. Confounding C. Information Bias D. Random Error PART A: Each of the following problems contains a potential error that could affect the accuracy of the results. a. Using the key below, indicate the most likely source of error in each problem based solely on the information provided. b. Provide a rationale for your answers, including an explanation of how the selection or information bias, confounding, or random error, as appropriate, could have biased the observed results. c. If A, B, or C is selected, indicate the likely direction of the bias or confounding (e.g., toward or away from the null value). Question 1 of 12 0.25 Points The authors of a cross-sectional study hypothesized that lack of regular exercise is associated with obesity in children. Their study of 12 children in Michigan, however, failed to show a statistically significant association between exercise habits and obesity (OR = 1.9, p = 0.11). A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 2 of 12 0.25 Points Please provide a rationale for your choice in question 1. Maximum number of characters (including HTML tags added by text editor): 32,000 Show/Hide Rich-Text Editor Question 3 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 1 A. negative B. positive C. N/A Question 4 of 12 0.25 Points In a case-control study of the relationship between intravenous drug use and HIV infection, the investigators discovered after the study that the case group had tended to underreport their drug use due to fears arising from previous convictions for drug-related violations. Underreporting was not a problem in the control group, however, which was not under medical supervision at the time. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 5 of 12 0.25 Points Please provide a rationale for your choice in question 4. (500 words) Question 6 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 4. A. negative B. positive C. N/A Question 7 of 12 0.25 Points A prospective cohort study followed 8,542 women for 10 years to determine if alcohol consumption increased the risk of breast cancer. No statistically significant association was found. Twelve thousand women had been enrolled in the study at its initiation, but 3,458 had withdrawn during the 10-year period. A follow-up of spouses, friends, and relatives of the women who withdrew revealed that more than 60% of the withdrawals had developed breast cancer and that nearly 84% were regular drinkers. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 8 of 12 0.25 Points Please provide a rationale for your choice in question 7. (500 words) Question 9 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 7. A. negative B. positive C. N/A Question 10 of 12 0.25 Points A large epidemiologic study found that elderly adults with dementia were more likely to develop liver cancer than those without dementia. The investigators, however, could offer no plausible biological mechanism for the association between dementia and liver cancer. Many of the subjects reported heavy drinking, however. A. Selection Bias B. Confounding C. Information Bias D. Random Error Question 11 of 12 0.25 Points Please provide a rationale for your choice in question 10. (500 words) Question 12 of 12 0.25 Points Please indicate the probable direction of the bias (if applicable) to your choice for question 4. A. negative B. positive C. N/A a) What kind of misclassification is this? b) Calculate the odds ratio and determine the direction of the bias, if any. Part 2 of 3 - PART B The tables below represent data from a case control study of a bone density and its association with hip fracture. The data have been stratified by age as follows: Age >=80 Hip Fracture No hip fracture Low bone density 72 20 High bone density 18 20 90 40 Age 65-79 Hip Fracture No hip fracture Low bone density 5 32 High bone density 5 128 10 160 Question 1 of 3 0.5 Points (a) Calculate the appropriate crude and stratum specific measures of association for this study. (b) Based on your calculations, does age confound the observed bone density - hip fracture association? (c) If so, in what direction? Question 2 of 3 0.5 Points Consider a case-control study of red meat consumption and prostate cancer. There are 350 cases of prostate cancer and 350 controls. 200 cases and 131 controls are known to have been regular consumers of red meat. Create the appropriate 2x2 table and calculate the odds ratio. Question 3 of 3 0.5 Points Now, assume that 10% of the true 'red meat consumers' users were misclassified as non-consumers and 10% of the actual non-consumers were misclassified as red meat consumers among both the cases and controls. a) What kind of misclassification is this? b) Calculate the odds ratio and determine the direction of the bias, if any. Part 3 of 3 - PART C Please read the following two articles before answering the questions noted below. Bruneau J, Lamothe F, et al. High rates of HIV infection among IDU participating in needle exchange programs in Montreal: results from a cohort study. American Journal of Epidemiology. 1997;146:994-1002. Lurie P. Invited commentary: le mystere de Montreal. American Journal of Epidemiology. 1997; 146: 1003-1006. Question 1 of 5 0.5 Points This paper provides results from several different study designs. Please briefly describe what these study designs were. (500 words) Question 3 of 5 0.5 Points What confounders were considered in this study? How did the investigators determine if these confounders were associated with the exposure of interest (NEP use)? (500 words) Question 4 of 5 0.5 Points What were the overall results of the study? What possible explanations were provided to explain these results? (500 words) Question 5 of 5 0.5 Points Read Peter Lurie's accompanying comment on this study. If you were a policymaker, how would the results of this study (in the context of Lurie's comments) influence your decision about whether to implement NEP in your community? (500 words)