A researcher conducts a cross-sectional survey and finds a significant association between dietary fat intake and the presence of gallstones on ultrasound. The primary limitation of this design for establishing causality is:
- A Inability to distinguish temporal sequence between exposure and outcome ✓
- B Selection bias from convenience sampling
- C Lack of a control group
- D Small sample size leading to type II error
Correct answer: A. Inability to distinguish temporal sequence between exposure and outcome
Explanation
Cross-sectional studies measure exposure and outcome simultaneously, making it impossible to determine whether the dietary pattern preceded gallstone formation or vice versa — the fundamental requirement for causal inference is temporal precedence. Lack of a control group characterises uncontrolled case series. Selection bias and sample size are potential but not the primary intrinsic limitation of the design for causality.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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