Hello! Welcome to the Epidemiology home page. The purpose of this
website is to give you a very simple introduction to epidemiology,
particularly to the basic types of epidemiological study designs.
- Measures the frequency of diseases and related events, such as
mortality, morbidity, hospital stays, and health behaviors
- Looks for causes and risk factors of disease to propose
effective strategies for disease prevention and control
Epidemiological studies are either observational or experimental.
Within observational studies, are the subsets of case control and cohort studies; within
the subset of cohort there can be retrospective or prospective cohort studies. An example
of an experimental epidemiological study is a randomized control trial.
Please see the pictorial representation of the different types of epidemiological studies below.
We will now explore the different types of epidemiological studies
in depth.
Observational
Case Control
Cohort: Retrospective,
Prospective
Experimental
Randomized Controlled Trial
Other Links
Observational Studies
In observational studies, the epidemiologist does not assign
a treatment but rather observes. For example, if the epidemiologist
wanted to see if smoking is related to lung cancer, she would not
be able to ethically assign people to smoke and not smoke, but rather
would observe the prevalence of who (smokers vs. non) develops cancer.
Case Control Studies
- Looks for causes of disease
- Looks at those with disease (case) vs. those without disease (control)
- The case group and control group should share the same potential causes/factors
that are not to be studied (e.g. age, socioeconomic status, sex, etc.), but should
not share factors that the epidemiologist suspects are causal factors
- The sample should be large enough so the findings can be extrapolated to a
larger population
- Tests to see whether a given causal factor is significant through the odds ratio-
the odds ratio is best explained through an example
Cohort Studies
- Looks for causes of disease
- Can have a control group or not
- There are two types: retrospective and
prospective
Experimental Studies
In experimental studies, the epidemiologist assigns subjects treatments. This
is in contrast to the observational study, where the researcher observes subjects and,
in a sense, 'waits'
for the 'treatment' or results to happen. One type of experimental study is the Randomized
Control Trial.
Other Links
Epidemiology General Lectures (under the topic 'Supercourse lectures' please select
epidemiology and biostatistics.
Guidelines for Good
Epidemiology Practices
Four Types of Epidemiological Studies