Skip to main content

Table 2 Contingency table showing the calculations of parameters of reliability of the screening test.

From: School screening and point prevalence of adolescent idiopathic scoliosis in 4000 Norwegian children aged 12 years

Population 4000

 

Children with Scoliosis

Children without scoliosis

Positive Screening

True Positive (TP) 22

False Positive(FP) 38

Negative Screening

False Negative(FN) 10

True Negative(TN) 3962

  1. Sensitivity = TP/(TP+FN) 22/32 = 0.69
  2. Specificity = TN/(FP+TN) 3962/4000 = 0.99
  3. PPV (positive predictive value) = TP/(TP+FP) 22/60 = 0.37
  4. NPV (negative predictive value) = TN/(FN+TN) 3968/3962 = 0.99
  5. LR+ (positive likelihood ratio) = Sensitivity/(1- specificity) 0.69/0.01 = 69
  6. LR-(negative likelihood ratio) = 1-sensitivity/(specificity) 0.31/0.99 = 0.31