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0:00
Hello everyone, this
is Dr. Rana Ismail.
I'm an adjunct
assistant professor
at Michigan State University,
College of Osteopathic
Medicine in the USA.
Today, we're going to cover the
overview of cohort study design.
0:16
In this lecture, we are
going to cover one of
the main observational
designs, the cohort study.
We're going to start by
defining what a cohort means;
how we do a cohort selection;
the two types of cohort studies;
what we use cohort studies for;
the pros and cons of
retrospective study design;
the things to consider
when choosing a
cohort study design;
the statistics used
in cohort studies;
and we're going to go over
some working examples.
Finally, we will cover
the proper interpretation
of relative risk,
which is the hallmark
statistic of cohort studies.
0:53
As you can see here, we have
a Roman legion which
here represents
a cohort or a group of people,
so it's a sample
of the population,
a legion from the army.
And this is exactly
what cohort means,
a group that you
follow over time.
1:09
What's a cohort? A
cohort is a group of
individuals or a well-defined
population subset
with a common or
shared feature that is
followed longitudinally
over time.
The cohort is a
representative sample of
the population, and there are two
ways you can follow the cohort.
Forward into the future, that is
prospective cohort, or follow
the cohort to the past-
that is a retrospective cohort.
These two designs, prospective
and retrospective,
prompt the researcher to collect
data on predictors of outcomes.
In the forward, prospective
manner - before the outcome
occurs and you measure
the outcome over time -
or in a retrospective
manner, when the outcome
has occurred and the
researcher collects data on
the detector valuables
in retrospect.
Examples of cohorts, for example, you
take a group of healthcare professionals,
a group of individuals with
certain conditions such
as for example diabetes.
Or, you take a group of
people with certain
characteristics,
let's say they're Millennials
that warn between
a certain time period or a group
of people who are
smokers or anything,
they have some exposure.
