I need to know if my answers are correct. – APP5.Samandari.M
Bias in Epidemiologic research
A cohort study was designed to look at the association of pesticides and the occurrence of childhood leukemia. Children living in rural areas wereDocument Preview:
APP5.Samandari.M
Bias in Epidemiologic research
A cohort study was designed to look at the association of pesticides and the occurrence of childhood leukemia. Children living in rural areas were followed and leukemia rates were compared between those children living in areas with high and low pesticide exposure. Pesticide exposure was considered high if it was over 20 “units” and low if it was under 20 “units.” The method used to quantify pesticide exposure was accurate to within +/- 12 units.
In this study children living in high pesticide exposure are being compared to children living in low pesticide exposure followed in time, but both group of individuals living in rural area such as south Asia or South Africa. Over time, outcomes may occur in both groups because they both have exposure (low and high), therefore analysis examines the frequency of the leukemia in the high exposure versus low exposure groups. The futures of cohort studies allow researchers to define the temporal result between exposure (pesticide) and outcome (leukemia) and avoid the risk of recall bias. This type of bias can occur in this cohort study when exposed subjects (high level of pesticide exposure) are more or less likely than unexposed (low level of pesticide exposure) subject to recall and report leukemia. Basically in this study participants are identical and classified with respect to exposure status, and it has to be followed overtime to ascertain of the disease leukemia. Bias can affect the measure of association in this case, because the children from both groups are exposed and it is hard to say if leukemia is related to low or high exposure especially when the high exposure is over 20.
2. Persons diagnosed as HIV positive or negative were interviewed about their number of lifetime sexual partners. The interviews occurred after they were told their HIV status
In this scenario interviewers are aware of the disease status (HIV +/-) of the subject and also aware of their…
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