COMPREHENSIVE REVIEW 2026 COMPLETE
QUESTIONS AND CORRECT ANSWERS
GRADED A+
◉ T/F: results of observational studies can provide the preliminary
data to inform the design and conduct a RCT when feasible.
Answer: true
◉ ______ observational study designs may have more generalizability
than an RCT if well conducted.
Answer: cohort
◉ Hierarchy of evidence.
Answer: meta-analyses > systematic reviews > RCT > cohort studies
> case-control studies > cross-sectional > case report > mechanistic
studies > editorials/expert opinion
◉ Exposure/outcome possibilities in cross-sectional design at time
of data collection.
Answer: exposed and outcome present
exposed and no outcome
,unexposed and outcome present
unexposed and no outcome
◉ Cross-sectional studies are often used to study what type of
conditions?.
Answer: frequent with long duration of expression
◉ Cross-sectional studies quantify _______ by cannot measure
incidence of disease.
Answer: prevalence
◉ Advantages of cross-sectional studies.
Answer: - quick and inexpensive
- ethically safe
- data on all variables collected at only one point in time
- multiple outcomes and exposures can be collected
- suitable for generating hypotheses
◉ Disadvantages of cross-sectional studies.
Answer: - can only establish association, not causality
- not able to investigate temporal relationship
,- highly susceptible to biases such as recall, observer, sampling, and
nonresponse
- confounders may be unequally distributed
- not suitable for rare or quickly emerging disease
◉ When are case-control studies preferred?.
Answer: disease outcomes are rare
◉ How is exposure data collected in case-control studies?.
Answer: retrospectively
◉ Describe how exposures are identified in case-control studies.
Answer: 1. collect study population
2. sort individuals into those with outcome and those without
outcome
3. determine who was exposed vs. unexposed in each group
◉ Advantages of case-control studies.
Answer: - quick and cheap as fewer people needed than cross-
sectional
- only feasible method for very rare disorders or long lag between
exposure and outcome
, ◉ Disadvantages of case-control studies.
Answer: - reliance on recall or records to determine exposure status
- confounders
- selection of control groups is difficult
- potential recall and selection bias
◉ How do nested case-controls differ from regular case-controls?.
Answer: - nested case-controls identify a cohort of individuals and
follow them over time to watch for cases
- once cases arise, a group of controls is selected from the same
cohort
- information on exposures is then collected and assess between
cases and controls
- major difference is that time as a factor can be accounted for
◉ What are cohort studies typically used to assess?.
Answer: assess the difference in the incidence of a disease over time
◉ In cohort studies data may be collected _______ or examined _______.
Answer: collected prospectively or examined retrospectively
◉ ________ is the strongest observational study design.