Calculation of diagnostic statistics using recent wheeze as the index of “disease present or absent” and airway hyperresponsiveness as the index of “test positive or negative”
| Disease present (recent wheeze) |
Disease absent | Total | |
| Test positive (AHR) | 337 (a) | 246 (b) | 583 |
| Test negative | 409 (c) | 2078 (d) | 2487 |
| Total | 746 | 2324 | 3070 |
Sensitivity = a/(a+c) = 0.45; specificity = d/(b+d) = 0.89; positive predictive value = a/(a+b) = 0.58; negative predictive value = d/(c+d) = 0.84; positive likelihood ratio = sensitivity/ (1—specificity) = 4.1.