A researcher wants to compare the proportion of diabetic patients with retinopathy between two groups (those with HbA1c > 8% versus those with HbA1c ≤ 8%). The expected frequency in one cell of the 2x2 table is 3. Which test is most appropriate?
- A Chi-square test
- B Fisher's exact test ✓
- C Paired t-test
- D McNemar's test
Correct answer: B. Fisher's exact test
Explanation
When any expected frequency in a contingency table is less than 5, the chi-square test is invalid due to approximation error. Fisher's exact test is the appropriate alternative for 2x2 tables with small expected cell frequencies. McNemar's test is for paired nominal data, and the paired t-test is for continuous paired data, neither of which applies here.
Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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