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What are three terms that are used to describe the timing of events in a cohort study in relation to
the initiation of the study? Prospective cohort
Retrospective cohort
ambidirectional
What are the difference between different kinds of cohort studies? Prospective -
participants are grouped on the basis of past or current exposure and are followed into the future
to observe the outcomes of interest.
Retrospective - both the exposures and outcomes have already occurred when the study begins.
Thus, this type of investigation studies only prior and not future outcomes.
What are the three sources for the group comparison group in a cohort study? internal
comparison group-unexposed members of the same cohort.
general population
comparison cohort -other cohort
,What is the best source for the comparison group in cohort study? internal >general >
comparison cohort
what measure is used to measure the occurence of the outcome in cohort study?
cumulative incidence
incidence rates
What kind of cohort study is most efficient for studying diseases with long induction and latent
periods? Retrospective
what is less vulnerable to bias? Prospective vs retrospective Prospective
What is counterfactual ideal? we want to compare the people who are the closest except
for the exposure like a same person
Because it is impossible for the same individuals to be exposed and unexposed simultaneously,
the investigator must select different sets of individuals for comparison.
What is the main strengths of cohort studies? they are efficient for studying rare exposures
allow investigators to evaluate multiple health effects of an exposure
, retrospective are efficient for studying disease with long induction and latent periods
What is the main weakness? they inefficient for studying rare outcomes
prospective cohoty are inefficient for studying diseases with long induction and latent period
retrospective cohort are vulnerable to biase
What is compared in traditional case control studies? What is compared in traditional case
control studies?
What is the difference between traditional and modern view of case study? Over the past 3
decades, the traditional view that a case-control study is a backward cohort study has been
supplanted by a modern view that asserts that it is merely an efficient way to learn about the
relationship between an exposure and a disease.
what is the purpose of the case studies? Its purpose is to provide information on the
exposure distribution in the population that produced the cases so that the rates of disease in
exposed and unexposed groups can be compared. Thus, the key comparison in the modern view
is the same as that of a cohort study.