Study Designs Flashcards
What are observational studies?
they observe the outcomes without intervening to affect them
What are experimental studies?
the researcher manipulates the exposure (usually a drug or treatment) to compare it to the standard of care
What are three types of observational studies?
- Cohort
- Case Control
- Cross-sectional
In cohort studies, subjects are selected based on their _______.
exposure status
True or False: Cohort studies follow participants in time.
True
Two types of cohort studies: ____ and ____
prospective
retrospective
Prospective Cohort studies compare disease prevalence in the ______ and _______.
exposed and unexposed
What are retrospective cohort studies?
they begin with the exposure of interest and probe back for exposure information
What are cohort studies particularly useful for?
assessing RARE EXPOSURE and rapidly fatal diseases
if the exposure hurt use a cohort
True or False: Cohort studies can evaluate multiple diseases/outcomes from a given exposure.
True
Cohort studies can calculate ____ among exposed and unexposed.
INCIDENCE #new cases during a specific time
iNcidence = New
True or False: Cohort studies are inefficient for rare diseases.
True,
inefficient for rare DISEASES but good for rare exposures
What are case-control studies?
Subjects are selected based on their disease status
True or False: In case-control studies, the diseased are compared to the non-diseased, which should differ only in past exposure.
True
Case-control studies can demonstrate risk ______ due to the retrospective nature of the design.
INDICATORS
not risk factors
Participants in a case-control study are chosen based on their _____ status. Therefore, at the beginning of the study, it is unknown who has been _____.
disease
exposed to the risk indicators
In a case-control study, the cases and controls must have had an equal chance of _____.
being exposed
Which study is best for rare EXPOSURES?
cohort
Which study is best for rare DISEASES?
case-control
True or False: Case-control studies can be used for diseases with a long latency period.
True
True or False: Case-control studies allow for the evaluation of multiple exposures that may increase risk for disease.
True
Case-control studies ____ directly compute incidence of disease in exposed/non-exposed persons. Cohort studies ____ directly compute incidence of disease in exposed/non-exposed persons.
Case-control= CANNOT Cohort= CAN
True or False: Case-control studies can establish temporal relationships.
False
Case-control studies are prone to errors in _______ and ______.
selection of cases
collection of information
What are cross-sectional studies?
point in time or “snapshot” studies that do not select patients based on exposure or disease
True or False: Cross-sectional studies are the most basic study design.
True
True or False: Cross-sectional studies do not need explained etiologic objectives.
True
What are the study designs for experimental studies?
Randomized Clinical Trial
Community intervention Trial
Randomized Clinical Trials are a sub-type of _____ studies because exposure is randomly assigned by the investigator.
cohort
_______ is the process by which each participant’s treatment is determined by an undescribed mechanism
Randomization
What is the primary purpose of randomization?
minimizing confounding- create groups that are not determine by any factor other than chance
_____ is the process by which the investigator and/or participant do not know which arm the participant is in
blinding
In a single-blind experiment, the ____ does not know which group the participant is in.
participant
In a double-blind experiment, _____ knows which group the participant is in.
neither the investigator or participant
What is information bias?
drawing different conclusions depending on their knowledge of which study arm a participant is in
What is selection bias?
study recruiters can be eager to recruit persons into the experimental arm based on their disease status
What are three important considerations in experimental studies?
- stopping rules
- sample size
- analysis and interpretation
What is a systematic review?
complete summary of the literature
What is a meta-analysis?
combined analysis of data from different studies following strict guidelines
