A prospective cohort study with a duration of 10 years found a vitamin supplement reduced the risk of cardiovascular dis

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A prospective cohort study with a duration of 10 years found a
vitamin supplement reduced the risk of cardiovascular disease.
However, subsequent studies, including high-quality randomised
controlled trials, have found the vitamin supplement has no effect
on the risk of cardiovascular disease. Please provide potential
explanations as to why the results from the initial cohort study
are inconsistent with later findings by referring to 1. random
sampling error; 2. selection bias; 3. measurement error; and 4.
confounding. You are provided with marks for explaining what the
issue is and for explaining how the issue could be relevant in
explaining the results. (3 marks for each issue for a total of 12
marks) (300-word limit). Please set your answers out under each of
the four headings.