Measuring Health in Populations - Lecture Seventeen Flashcards
Cross-sectional and Ecological Studies
Epidemiology
The study of the distribution (descriptive epidemiology) and determinants (analytic epidemiology) of health-related states or events in specified populations
Descriptive epidemiology
Person, place and time
Answers what, who, where and when
Analytic epidemiology
Associations (exposures and outcomes), causation
Answers why
Cross-sectional studies
Measure exposures and/or outcomes at one point in time
What do cross-sectional studies measure?
Prevalence
Prevalence calculation
Number of people with the disease at a given point in time / time number of people in the population at that point in time
What are cross-sectional studies used for?
To describe the prevalence of exposures or health conditions in a population
To compare the prevalence among different groups in a population
To generate hypotheses
To plan health services
The sample population
People who meet the requirements and are in the study
The exposed group
People who have the potential risk factor that the study is interested in
Limitations of cross-sectional studies
Temporal sequencing
Measures prevalence not incidence
Not good for studying rare outcomes and exposures
Not good for assessing variable and transient exposures or outcomes
Why do cross-sectional studies?
Can assess multiple exposures and outcomes
Depends on your research question
Can be less expensive than some other study designs
Relatively quick
Depends on your research question (cross-sectional studies)
Prevalence, and distribution of prevalence in the population
Stable exposures and outcomes
Hypothesis generating
Ecological studies
Compare exposures and outcomes across groups not individuals
What are ecological studies used for?
To compare between populations
To assess population level factors
To consider hypotheses
Limitations of ecological studies
Ecological fallacy
Cannot control for confounding and cannot show causation
