A 2 by 2 contingency table from a study has an expected frequency of 3 in one cell. The total sample size is 25. The most appropriate test to analyze this data is:
- A Chi-square test with Yates correction
- B Chi-square test without correction
- C Fisher's exact test ✓
- D McNemar's test
Correct answer: C. Fisher's exact test
Explanation
When any expected cell frequency in a 2 by 2 table is below 5, especially with a small total sample size, Fisher's exact test is preferred because the chi-square approximation becomes unreliable. Yates correction improves the chi-square approximation but is still inadequate when expected frequencies are very low. McNemar's test is for paired or matched categorical data.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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