Study Designs Flashcards
This study measures the prevalence of a certain outcome in a population at a point in time.
Cross-sectional studies
This study measures exposure and outcome at the same time at an individual level.
Cross-sectional studies
This study compares exposure and outcomes across large groups.
Ecological study
What studies can be used to generate hypotheses?
Cross sectional and ecological studies
What are some limitations of cross sectional studies? (3)
1) cannot measure incidence
2) not good for rare outcomes and transient exposures
4) cannot establish temporal sequence (as outcome and exposure measured at the same time)
What are some strengths of cross-sectional studies? (4)
1) used to generate hypothesis
2) can measure multiple exposures and outcomes at a time
3) measures prevalence
4) quick and cheap
This is a concept that describes when characteristics from a group level are attributed/applied to the individual
Ecological fallacy
What are the strengths of ecological studies? (4)
1) can compare between groups
2) good for population level exposures
3) quick and easy to do (data is routinely collected)
4) good for considering hypothesis
What are some limitations of ecological studies? (3)
1) ecological fallacy (also that every data point is a population)
2) confounding
3) cannot show causation
This study is when individuals are defined by their exposure status to a suspected risk factor.
Cohort study
What study would be appropriate to use if you were trying to figure out the effects of living in a decile 10 environment on influenza rates throughout 5 years?
Cohort study
- because it involves an exposure and a follow up time.
- those are the 2 main aspects of a cohort study
What are the 2 types of cohort studies and what is the difference between both?
1) Prospective cohort studies - start with exposure and see if the person will develop the outcome (through follow up)
2) Retrospective cohort studies - start with an outcome of interest and work out from then what kind of exposures (in a person’s life) would have led to the outcome.
- working backwards essentially
- still focused on the exposures
Why might someone not be considered eligible to be in a cohort study?
1) they already have the outcome (you must be free of outcome to be part of prospective cohort study)
2) they have outcome that cannot be developed (like prostate cancer)
What are some strengths of a cohort study? (4)
1) can establish a temporal sequence
2) can examine multiple outcomes from an exposure
3) can calculate incidence (so RR and RD as well)
4) good for studying rare exposures
What are some limitations of cohort study? (4)
1) loss to follow up
2) misclassification of exposure/outcome
3) not good for rare outcomes and transient exposures
4) time consuming and expensive