In a study comparing a new diagnostic test to the gold standard in 200 patients, 60 have the disease. The test correctly identifies 48 true positives and 128 true negatives. What is the specificity?
- A 91.4% ✓
- B 80%
- C 75%
- D 62.5%
Correct answer: A. 91.4%
Explanation
Specificity = True Negatives / (True Negatives + False Positives) = TN / (total without disease). Total without disease = 200 – 60 = 140; TN = 128; FP = 140 – 128 = 12. Specificity = 128/140 = 91.4%. Sensitivity = 48/60 = 80%.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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