Chapter 14: Key Approaches Flashcards
What is an experimental study?
-researcher intervenes to change exposure then observes/measures what happens (Cause-Effect)
What is an observational study?
- researcher observes/measures exposure and outcome (does not manipulate)
- environment is not changed
- not a “true” experiment
- associations
What are the two types of observational studies?
- descriptive
- analytical
What are descriptive studies?
- help identify patterns and generate hypothesis
- case report, surveys, fact-finding inquiries
- frequency and distribution of single variables
What are analytical studies?
- groups are being compared
- aims to associate exposure/intervention and outcome
What are case reports?
- An in-depth analysis of a single individual, unit, or event
- Direct observation and questioning
- Provide considerable detail
- Usually concern rare events
What are the challenges of case reports?
A) difficult to draw clear causal linkages;
B) generalizability of findings;
C) potential for observer bias
What are the three types of analytical studies?
- Cohort (prospective)
- Case-Control
- Cross-Sectional
What is the goal of cohort (prospective studies)?
- characterize (observe) exposures in participants and then track them over time
- compare exposed vs. controls
What is the goal of case-control studies?
- enroll participants with disease or outcome and find matched controls
- compare previous exposures between groups
What is the goal of cross-sectional studies?
- enroll participants and measure exposures and health simultaneously
- snapshot
Explain cohort studies and provide pros and cons
- Longitudinal or prospective
- Start with an exposure and then follow group overtime; compare between exposed and un-exposed
- E.g., Nurses Health Study
- Pros: can match subjects at baseline; establish timing of events; can standardize exposures
- Cons: associative study (not causal); blinding is difficult; not randomized; rare diseases need large sample size and long follow-up
Explain case-control studies and provide pros and cons
- Retrospective (opposite of cohort)
- Start with an outcome/disease and then work backwards to identify possible causes
- Pros: relatively quick and cheap; most feasible for rare disorders or outcomes with long latency period; fewer subjects needed than other studies
- Cons: associative study (not causal); reliance on recall and records to determine exposures (past diet??); not randomized; control groups hard to find; selection bias
Explain cross sectional studies and provide pros and cons
- Study at one point in time to determine if there is an association between exposure and health
- Pros: relatively cheap and simple
- Cons: associative study (not causal); recall bias problems; confounders may be unequally distributed
What is the STROBE Checklist?
Strengthening The Reporting of Observational studies in Epidemiology
