In a descriptive study, what type of data is typically collected?

Correct Answer: B

Rationale: Descriptive studies (B) collect quantitative data (e.g., case counts) to describe patterns. A is qualitative, C is experimental, D is broad.

Correct Answer: A

Rationale: Descriptive studies often collect qualitative data (A) to describe patterns (e.g., case reports), though quantitative (B) is also common. C and D are less typical.

Correct Answer: D

Rationale: Reverse causation bias (D) occurs when outcome affects perceived exposure (e.g., disease prompting recall). A is selection, B is broad, C is recall.

Correct Answer: C

Rationale: IRBs (C) review protocols for ethics (e.g., consent, safety). A, B, and D are not their roles.

Correct Answer: D

Rationale: Raising the cutoff (D) makes the test stricter, increasing specificity (fewer false positives) but decreasing sensitivity (more false negatives). A, B, and C defy trade-off.