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Case Control and other study design
Made by:Momal Sheikh Nawab khatoonZiyad Furqan
Study Design
Case Control and Cohort Studies
Case ControlAdvantage :• Less Expensive• Efficient for studying rare diseaseDisadvantage:• Inappropriate when disease for specific
exposure not known• Exposure measurement after disease
Cohort ControlAdvantage:• Exposure status determined before disease
detection• Subjects selected before disease detection• Study several outcome of each exposureDisadvantage• Expensive and Time consuming• Inefficient for rare disease
Case•
Select group of
children under 5 from
Village and clinic
•Check children have
diarrhea
•Exposure: Source of
suspected water and
other water
B lind ed N o t b lind ed
R a nd o m ised N o t ran d om ised
C o n tro lled N o t co n tro lled
T ria l
Types of TrialsClinical study design is the formulation of trials and experiments, as well as observational studies in medical, clinical and other types of research (e.g., epidemiological) involving human beings.
Controlled• An experiment or clinical
trial in which two groups are used for comparison
purpose. • one group of participants
is exposed to a substance (e.g. a pollutant) while those in the "control"
group are not
Uncontrolled researchers have no such
control over whether their subjects receive the treatment
being investigated. �Uncontrolled studies thus are
subject to worries about confounding variables.
Potential bias in case controll studies
Selection bias can occur in a case-control study if controls are more (or less) likely to be selected if they have the exposure.
Selection Bias
Door-to-door survey of neighborhood around the hospital during work day.
Information BiasIn epidemiology, Information bias refers to bias arising from measurement error.
Recall Bias
• involves interviews or questionnaires, regarding events or experiences from the past
• Patient have accurate recall.
Limitation Bias
• The person being interviewed may simply not have the information being requested
ECOLOGIC
STUDIES
CROSS-SECTIONAL
STUDIESCROSS-SECTIONAL
STUDIES
factor present
Other Study
Design
CASE-
CROSSOVER
DESIGN
Study only exists at this point in time
Case Crossover
USED FOR
STUDING THE
ETIOLOGY OF
ACUTE OUT COME
SUCH AS
MYOCARDIAL
INFRACTION OR
DEATHS FROM
ACUTE EVENT
OVER A SHORT
PERIOD OF TIME.
Ecological Studies
Example: The Outbreak
of Influenza and later
development of acute
lymphocytic leukemia in
a child not known if the
mother of any of these
children had influenza
during their pregnancy.
What we are missing is
the individual data of
exposure