observational study

What is the main difference between observational studies and randomized controlled trials (RCTs)?

• RCTs actively control treatment assignment through randomization

• Observational studies have larger sample sizes

• RCTs are always done retrospectively

• Observational studies are more expensive

In case-control studies, what is a key potential source of bias?

• Treatment costs

• Sample size

• Selection of controls

• Study duration

What is "Simpson's paradox" in observational studies?

• When results differ between subgroups and combined data

• When two studies contradict each other

• When treatment effects are too small

• When patients drop out of studies

Which method can help reduce confounding in observational studies?

• Increasing sample size

• Propensity score matching/weighting

• Changing outcome measures

• Extended follow-up periods

According to Hill's criteria for causality, which is NOT one of the criteria?

• Temporal relationship

• Study cost

• Dose-response relationship

• Consistency across studies