Biostatistics & Research · single question
A diagnostic test specificity calculation gives: 3500 ÷ (3500 + 35) × 100. What is the specificity?
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Correct answer: C. 99%
- A. 20% would indicate very poor specificity. The calculation 3500/(3500+35) ≈ 99%.
- B. Close but not correct. The exact calculation: 3500/3535 = 0.9901 = 99%.
- C. Specificity = True Negatives ÷ (True Negatives + False Positives) = 3500 ÷ (3500 + 35) = 3500 ÷ 3535 = 0.9901 × 100 = 99%.
- D. Incorrect. Specificity = TN ÷ (TN + FP) = 3500 ÷ 3535 = 99%.
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