Assessment results cutoff −2 SD


Observer 1


Observer 2

Delayed

Not Delayed

Total

A

B
 
True positive

False positive
 
3

0

3

C

D
 
False negative

True negative
 
15

83

98

Total

18

83

101

 Sensitivity = A / A + C 3/18=17%.
 Specificity = D / B + D 83/83=100%.
 Total Agreement = A + D / A + B + C + D (3+83)/101=86%.
 Positive Predictive Value = A / A + B 3/3=100%.
 Negative Predictive Value = D / C + D 83/98=84%.
 Overreferral = B / A + B + C + D 0/101=0%.
 Underreferral = C / A + B + C + D 15/101=15%.
 Likelihood ratio—positive = Sensitivity / (1 – specificity) incalculable.
 Likelihood ratio—negative = (1 – sensitivity) / specificity .83.