Chapter 7: Observational Studies Flashcards
Does descriptive studies generate hypotheses, true or false?
True
Does analytic studies test hypotheses, true or false?
True
What is descriptive epidemiology?
Means organizing, summarizing, and describe epidemiologic data by person, place, and time.
What are descriptive factors?
Age, sex, and occupation (person characteristic)
Residence, work, environmental factors (place characteristics)
Clinical symptoms, diagnosis, reporting, testing (time)
What study design is included in descriptive?
Ecological, case report, case series, and cross sectional.
What study design is included in analytic?
Clinical trial, cohort, case-control.
What are case reports and case series?
One report or more series focused on a specific disease or outcome, which typically occurs in a natural clinical setting.
What are the strengths of case reports and case series?
- Relatively quick
- Inexpensive
- May identify new/ emerging diseases
- May generate hypotheses for analytic studies
- May provides insight into disease mechanisms
What is the weakness of case reports and case series?
- No comparison groups
- Small study population (rare/emerging disease)
- Temporal ambiguity
What is ecological studies?
Involve aggregated data at the population level and focuses on the comparison of groups.
What is the strength of ecological studies?
- Easily conducted
- Inexpensive
- Able to pull different groups for comparison
What is the weakness of ecological studies?
- Results can be diffcult to interpret
- Ecological fallacy
- Lack of adequate data
- Temporal ambiguity
What is ecological fallacy?
- When aggregated-level results are used to draw conclusions about individual-level relationships.
- Ecological studies assume heterogeneity of exposures.
What are cross-sectional studies used for?
Usually used to compare different exposure subpopulations.
When and why do we conduct a cross sectional study?
- To gather data on the prevalence of health behaviors, risk factors, and disease presence.
- To learn about a population.
- To help monitor trends over time.
What are the strengths for cross-sectional studies?
- Relatively quick with no long periods of follow-up
- Inexpensive
- Multiple outcomes can be researched at one time
- May generate hypotheses for analytic studies
- Long duration and common disease are easily captured
What are the weakness of cross-sectional studies?
- Can’t establish causal relationships
- Subject to selection bias
- Subject to non-response bias
- Subject to survival bias
- Short duration disease may be underrepresented
When and why do we conduct a case control study?
- To study rare disease
- To study multiple exposures that may have a relationship with a single outcome
- When funding or time to study the disease of interest is limited
What is odd ratios?
Identifies that their is a statistical association between a disease and an exposure.
Odd ratios
Quantify the probability of and association between a disease/outcome and an exposure.
What is selection bias?
Doesn’t fully repersent every group.
Recall bias
Differential accuracy of recall between cases and controls.
Interview bias
Interview probes cases differently than controls.
