Skip to main content

Table 3 Contingency table for the observer agreement for cognitive impairment at cut- off -1SD

From: Validation of a culturally modified short form of the McCarthy Scales of Children’s Abilities in 6 to 8 year old Zimbabwean school children: a cross section study

Assessment at cut off – 1SD

Observer 1

Observer 2

Delayed

Not Delayed

Total

A

B

13

True positive

False positive

 

9

4

 

C

D

88

False negative

True negative

 

9

79

 

Total

18

83

101

  1. Sensitivity = A / A + C 9/18= 50%.
  2. Specificity = D / B + D 79/83=95%.
  3. Total Agreement = A + D / A + B + C + D (9+79)/101=87%.
  4. Positive Predictive Value = A / A + B 9/13=69%.
  5. Negative Predictive Value = D / C + D 79/88=89%.
  6. Over-referral = B / A + B + C + D 4/101=4%.
  7. Under-referral = C / A + B + C + D 9/101=9%.
  8. Likelihood ratio—positive = Sensitivity / (1 – specificity) 10.
  9. Likelihood ratio—negative = (1 – sensitivity) / specificity 0.53.
Back to article page