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Table 5 Probability increases (%) for P(1+) and for P(0-) in relation to prevalence and LRs

From: Questioning the “SPIN and SNOUT” rule in clinical testing

 

PPV

probability increase (%) for P(1+)

prevalence

prevalence

SE

SP

LR+

0.2

0.4

0.6

0.8

0.2

0.4

0.6

0.8

0.8

0.8

4.00

0.50

0.73

0.86

0.94

0.30

0.33

0.26

0.14

0.4

0.8

2.00

0.33

0.57

0.75

0.89

0.13

0.17

0.15

0.09

0.8

0.4

1.33

0.25

0.47

0.67

0.84

0.05

0.07

0.07

0.04

0.4

0.4

0.67

0.14

0.31

0.50

0.73

−0.36

−0.42

−0.36

−0.21

   

NPV

   

probability increase (%) for P(0-)

   
   

prevalence = P [1]

   

1-prevalence = P(0)

   

SE

SP

LR-

0.2

0.4

0.6

0.8

0.8

0.6

0.4

0.2

0.8

0.8

0.25

0.94

0.86

0.73

0.50

0.14

0.26

0.33

0.30

0.4

0.8

0.75

0.84

0.67

0.47

0.25

0.04

0.07

0.07

0.05

0.8

0.4

0.50

0.89

0.75

0.57

0.33

0.09

0.15

0.17

0.13

0.4

0.4

1.50

0.73

0.50

0.31

0.14

−0.07

−0.10

−0.09

−0.06

  1. Diagnostic test calculators are available on the internet to determine SE, SP, LRs and or to determine post-test probabilities given prevalence and test characteristics [12, 13].