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Biostatistics & Research · single question

A researcher calculates sensitivity as 870/(870+45) = 95%. What does this value tell you about the test?

  1. The test correctly identifies 95% of people without the disease
  2. The test correctly identifies 95% of people WITH the disease
  3. 95% of positive test results are true cases
  4. 5% of all patients are correctly diagnosed
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Correct answer: B. The test correctly identifies 95% of people WITH the disease

Sensitivity = True Positives / (True Positives + False Negatives) = TP/(TP+FN). In this case: 870 true positives / (870 true positives + 45 false negatives) = 95%. This means the test correctly identifies 95% of patients who truly have the disease. A highly sensitive test is used to RULE OUT disease (if negative, disease is unlikely — 'SnNout': Sensitive test, Negative result, rules Out disease).
  • A. ❌ Identifying people WITHOUT the disease is specificity (TN/(TN+FP)), not sensitivity.
  • B. ✅ CORRECT – Sensitivity measures the ability to correctly identify TRUE POSITIVES — people who actually have the disease.
  • C. ❌ The proportion of positive test results that are true cases is the positive predictive value (PPV), not sensitivity.
  • D. ❌ This description doesn't match any standard biostatistics definition.

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