Study designs Flashcards
What should be considered when setting objectives/hypothesis for a study?
Estimation of how common the disease is
What are the risk factors associated with the disease
What should be considered when designing a study?
Hypothesis Time Cost Resources Welfare considerations
What is a cross-sectional study?
Observational study that analyses data from a population at a specific point in time (can be past or present)
What are case control studies?
Individuals classified by disease status (cases = diseased, controls = non-diseased)
Analysis quantifies association of disease with each risk factor
What cannot be estimated from case-control studies?
Incidence
Prevalence
What could cause invalid results in a case-control study?
Incorrect selection of control group or case group
What are cohort/longitudinal studies?
Follow a group over a time period
Cohort studies can be fixed or dynamic. What do these mean?
Fixed = follow one group for full time period, exposure doesn't change Dynamic = not all of group followed for full time period, exposure may change
What are the advantages of a cross-sectional study?
Fast and cheap
Estimates prevalence of exposure and outcome
What are the disadvantages of a cross sectional study?
Can’t estimate incidence
Not for short or rare disease
What are the advantages of a case-control study?
Can use existing records
Good for rare/long diseases
Assess multiple exposures
What are the disadvantages of a case-control study?
Can’t calculate incidence or prevalence
Selection bias and recall bias
What are the advantages of cohort studies?
Can calculate incidence
Can assess multiple exposures
Good for rare exposures
What are the disadvantages of a cohort study?
Affected by loss to follow up
Takes a long time
