Study Designs Flashcards
(31 cards)
What studies are allocated/assigned to receive a treatment or exposure in order to study the effect?
Experimental
Reasons why subjects may be selected for inclusion in a study…
1) because they represent a population
2) their exposure status
3) their outcome status
What is the goal of sampling?
To select a sample that represents the population or group (exposure or outcome) being studied
What type of studies are the best for demonstrating causality?
Experimental
How do we measure the amount of disease occurrence? (Aka risk)
Incidence
How are experimental studies essentially free of bias and confounding?
1) random allocation
2) blind or double-blind
What two broad types of observational study designs compare groups?
- Groups of populations
2. Groups of individuals
Observational study designs are a misnomer in the sense that …
Investigators may measure, take samples, ask questions… (breaching “observation”)
What type of study compares groups of populations and does not make measurements on individuals?
Ecological
What is a major disadvantage of ecological studies?
Ecological fallacy*
-relationships observed at population levels may not hold true at the individual level
What are “epidemiology” synonyms for Experimental studies?
“Randomized controlled trials”
“Clinical trials”
What type of study might be used to best evaluate treatments/exposures involving nutrition, vaccine, antibiotics, etc?
Experimental
How are groups compared in analytical studies?
1) comparison on the basis of exposure
2) comparison on the basis of outcome
Cohort studies are selected on the basis of…?
Exposure
What studies are individuals selected to represent a population?
Analytical cross-sectional
Measure of disease occurrence in analytical cross-sectional studies?
Prevalence
What type of study are individuals selected to represent outcome groups?
Case-control
What is a way to control factors for confounding without allocating?
Matching! (I.e. Case-control studies)
What is a staple advantage of case-control studies?
They’re good for studying RARE diseases where it’s difficult to get enough cases for stat analysis
Retrospective vs. Prospective cohort studies…
Retrospective and prospective cohort studies select individuals based on their exposure, but how is retrospective cohort different?
The outcome is already established; the measure of association is PREVALENCE Ratio*
(In prospective cohort, the measure of association is relative risk)
What 2 types of study designs use INCIDENCE as the measure of dz exposure?
Prospective cohort;
Clinical trial
What type of study uses ODDS as a measure of dz exposure?
Case control!
What type of study uses PREVALENCE/ODDS as a measure of dz exposure?
Cross-sectional
What type of study uses PREVALENCE as the measure of dz exposure?
Retrospective cohort
