Randomized controlled trial vs Observational cohort and cross-sectional studies
How to tell Randomized controlled trial and Observational cohort and cross-sectional studies apart when a board question makes them look alike.
RCT assigns exposure; cohort observes exposure over time; cross-sectional snapshots one time point.
Side by side
Randomized controlled trials assign interventions randomly, reducing confounding and supporting causal inference.
Cohort studies observe exposure groups over time; cross-sectional studies measure exposure and disease at one time point.
Randomized controlled trials assign interventions randomly, reducing confounding and supporting causal inference.
Cohort studies observe exposure groups over time; cross-sectional studies measure exposure and disease at one time point.
The repair move
Before naming the answer, force the stem through the separator: RCT assigns exposure; cohort observes exposure over time; cross-sectional snapshots one time point.
Try a free question
CoreInvestigators want to test whether a new antihypertensive drug reduces stroke. They enroll 5,000 patients with hypertension, randomly assign them to drug vs placebo, double-blind both patients and investigators, and follow for 5 years measuring stroke incidence. Which study design is this?
Show answer and explanation
Answer: A. Randomized controlled trial. Randomized controlled trial (RCT) is the gold standard for testing intervention efficacy. Random assignment balances both measured and unmeasured confounders between groups, allowing causal inference. Blinding (single, double, triple) reduces bias. Best evidence for treatment efficacy; cannot test exposures that cannot be ethically randomized (smoking, asbestos).
Why the other choices are tempting
- B. Prospective cohort observes exposure status without randomization; vulnerable to confounding.
- C. Case-control starts with disease status.
- D. Cross-sectional measures exposure and outcome at one time.
- E. Case series reports outcomes in a few cases without comparison group.
Flashcards
Tap a card to flip it.
What clue supports Randomized controlled trial?
Choose Randomized controlled trial when the stem gives this pattern: Randomized controlled trials assign interventions randomly, reducing confounding and supporting causal inference.
What clue supports Observational cohort and cross-sectional studies?
Choose Observational cohort and cross-sectional studies when the stem gives this contrasting pattern: Cohort studies observe exposure groups over time; cross-sectional studies measure exposure and disease at one time point.
Quick answers
What is the fastest way to tell Randomized controlled trial from Observational cohort and cross-sectional studies?
RCT assigns exposure; cohort observes exposure over time; cross-sectional snapshots one time point.
What is the key clue for Randomized controlled trial?
Randomized controlled trials assign interventions randomly, reducing confounding and supporting causal inference.
What is the key clue for Observational cohort and cross-sectional studies?
Cohort studies observe exposure groups over time; cross-sectional studies measure exposure and disease at one time point.