Descriptive, cross sectional and ecological studies. Flashcards
What is the ‘Epidemiological transition’?
Replacement of infectious diseases with chronic diseases over time.
Descriptive studies can define patterns in terms of ___, _____ and ___.
Time, person, place.
Can you make any causal inference.with a case report?
No.
What is the other name for ecological studies?
Correlation studies.
What level do ecological studies work at?
Aggregate level.
What is ecological fallacy?
When group associations do not lead to individual level associations. (Also known as ecological bias and aggregation bias).
When are ecological studies useful?
When the variable of interest occurs at the population level.
Name three things that can be investigated in an ecological study.
- Food availability.
- Socioeconomic status and health.
- Effect of tax intervention on policy.
When are ecological studies not ideal.
When variability in a population is large.
Name four disadvantages of an ecological study.
- Ecological fallacy.
- Secondary data from different sources may not be comparable.
- Disease occurrence could proceed exposure.
- Collinerality.
What is collinerality?
Some sociodeomographic and environmental variable are more highly populated at the group level rather than the individual level.
Name five advantages of an ecological study.
- Relatively inexpensive.
- No follow up.
- High risk demographics targeted,
- Some environmental factors can be hard to measure at the individual level.
- Creates hypothesis about disease aetiology.
What is studied at the same time in cross sectional studies?
Exposure and outcome.
What can you not calculate from cross sectional studies and why?
Incidence proportions and incidence rates. You can not calculate these as both require you to know follow up time.
Why are cross sectional studies less biased then other types of studies?
Looks at general population instead of just those seeking medical care. You still however may not reach the entire population.
