
Prior probability (odds): 
5% (0.1) 

POSITIVE TEST: 
Positive Likelihood ratio: 
10 
Est. 95% confidence interval: 
[9.99,10] 
Posterior probability (odds): 
34% (0.5) 
Est. 95% confidence interval: 
[34%,34%] 
(~ 1 in 2.9 with positive test 
are sick) 

NEGATIVE TEST: 
Negative Likelihood ratio: 
0.00 
Est. 95% confidence interval: 
[0.00,0.00] 
Posterior probability (odds): 
0% (0.0) 
Est. 95% confidence interval: 
[0%,0%] 
(~ 1 in 1.0 with negative test 
are well) 

Odds = Probability / (1Probability) 
+LR = Sensitivity / (1  Specificity) 
LR = (1  Sensitivity) / Specificity 
Posterior Odds = Prior Odds x LR 
Added 0.5 to cells to estimate CI's 
