alldefinitionsand citation come from text book and provided info (clear complete answers)
KNOWLEDGE-BASED QUESTION
Which of the comparison groups is the best type (less biased) to use in a cohort study? Please explain.
1. Please answer the following questions regarding cohort studies.
A. Give the definition of a cohort study.
B. Name and define the different types of cohort studies with regard to timing, feasibility, and population type.
C. Describe the advantages and disadvantages of prospective and retrospective cohort studies.
D. Describe some population groups from which the exposed study participants might be selected.
E. What is the main principle underlying the selection of a comparisongroup for a cohort study?
F. Name and define the three types of comparison groups. Which of these is considered the "best" source for a comparison group and why?
APPLICATION-BASED QUESTIONS
2. Suppose that a study of oral contraceptive (OC) use and development of bacteriuria was conducted among 47,800 women, all of whom were initially free from bacteriuria. At the start of the study, the women were surveyed to determine whether or not they currently used OCs. 9,640 were using OCs and 38,160 were not. By the end of the follow-up period, a total of 540 of the OC users and 1,540 of the non-users had developed bacteriuria.
1. Is this a cohort study or an experimental study?
2. Set up the two-by-two table for these data.
3. Calculate the risk ratio describing the strength of the relationship between OC use and bacteriuria.
4. Based on your answer above, do you think that OC users are at higher risk of developing bacteriuria than non-users?
3. Researchers examined the effect of working for pay on adolescent tobacco use over two years (see American Journal of Public Health paper by Ramchand et al. (2007). PDF link is below). Of the 52 adolescent workers with no work to work, 15 had tobacco use. Of the 111 adolescent workers with no work in both years, 4 had tobacco use.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2040355/pdf/0972056.pdf
Table 3 shows the characteristics of incident tobacco use among adolescent workers.
1.
Fill in the 2x2 table to evaluate the association between exposure of no work to work and tobacco use in this cohort.
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Tobacco Use
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No Tobacco Use
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Total
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No work to work
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No work in both years
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2.
Calculate and interpret the relative measure of association from your 2x2 table. Compare your results to Table 3.
3.
Note the wide confidence intervals (CI’s) in Table 3. Should you conclude there is an elevated risk of tobacco use based on the relative risk and CI’s?
4.
What conclusions can you make about the risk of tobacco use among adolescents and working?