Prevalence = 

Prevalence, sensitivity, and specificity must each be entered as a proportion.  
Sensitivity =  
Specificity = 
For any particular test result:  
probability that it will be positive  
probability that it will be negative  
For any particular positive test result:  
probability that it is a true positive ["positive predictive value"]  
probability that it is a false positive  
For any particular negative test result:  
probability that it is a true negative ["negative predictive value"]  
probability that it is a false negative  
likelihood Ratios: [definitions]  
Conventional Positive  
Conventional Negative  
Positive [weighted for prevalence]  
Negative [weighted for prevalence] 
Home  Click this link only if you did not arrive here via the VassarStats main page. 
= 
conditional probability of positive test result if the condition is present conditional probability of positive test result if the condition is absent  = 
sensitivity
1specificity 
= 
conditional probability of negative test result if the condition is present conditional probability of negative test result if the condition is absent  = 
1sensitivity
specificity 
= 
probability that a positive test result is a true positive probability that a positive test result is a false positive  = 
(prevalence)(sensitivity)
(1prevalence)(1specificity) 
= 
probability of false negative result
probability of true negative result  = 
(prevalence)(1sensitivity)
(1prevalence)(specificity) 