EXPECTED VALUE OF PERFECT INFORMATION :: EVPI

 

(c) Health Decision Strategies, LLC.


  Beta Test - Not for Official Use
  Data Entry Form

  :: You can enter new values in the yellow boxes.  
  :: Calculated results will appear in the blue boxes.


Disease Probability   Variable Value  
  Prob_Rx_Needed   Basic_Test  
  Prob_Rx_Unneeded   Perfect_Test  
  No_Test  
  No_Treat  
  Treat  
  Treat_Later  
 
  Outcome  
      Value  
  Rx_Needed            
         
  No_Treat and No_Test   EV=  
      C    
  EV=    
      Rx_Unneeded            
         
      EV=  
     
       
      Test Positive(TP)_Treat  
               
        Rx_Needed       EV=  
          C    
        EV=    
          Test Negative(FN)_NoTreat  
             
  Basic_Test       EV=  
      C    
  EV=        
          Test Positive(FP)_Treat  
                 
        Rx_Unneeded       EV=  
Treatment       C    
Potential   D     EV=    
        Test Negative(TN)_NoTreat  
  =EV      
      EV=  
     
       
      Rx_Needed            
             
  Treat_Without_Test     EV=  
      C    
  EV=    
      Rx_Unneeded            
         
      EV=  
     
      1.0  
      Test Positive(TP)_Treat  
               
      Rx_Needed       EV=  
          C    
      EV=   0.0  
          Test Negative(FN)_NoTreat  
             
  Perfect Test         EV=  
  C    
  EV=       0.0  
      Test Positive(FP)_Treat  
           
  Rx_Unneeded       EV=  
  C    
  EV=   1.0  
  Test Negative(TN)_NoTreat  
     
  EV=  

:: Example of bar graph generated by EVPI calculator:    
 
Example of bar graph generated by EVPI calculator>
     
     
     
     
     
     
     
     
     
     
     
     
                               


Bar Graph Data Table Explanation:
  Options EV Of Treatment Plan Option EV of Option Minus Perfect Test                
1 << Compared to Option 1, the Perfect Test is Worth This Value  
2 << Compared to Option 2, the Perfect Test is Worth This Value  
3 << Compared to Option 3, the Perfect Test is Worth This Value  
4 <<< Value of Perfect Test
 
         


Test Statistics can be modified in yellow boxes.  
Patient Status
Patient Status
Sensivitty = TP/(TP+FN)
 
This value is modified if you change the TP for the Basic Test above.
 
Rx Needed
Rx Unneeded
Specificity = TN/(TN+FP)
    Pos Neg This value is modified if you change the TN for the Basic Test above.
Test Result
Pos
Sensitivity is the proportion of patients who had a positive test result in those who need the treatment.
  Neg
       
Specificity is the proportion of patients who had a negative test result in those who do not need treatment.
       
             
             
Definitions   Rx Needed Rx Unneeded      
        TP = True Positive = test is positive and patient needs treatment
        TN = True Negative = test is negative and patient does not need treatment.
    D+ D- FP = False Positive = test is positive but patient does not need treatment.
Test Result T+ TP [a] FP [b] FN = False Negative = test is negative,  but patient needs treatment.
  T- FN [c] TN [d]  
             
             
             



Developed By HDS

 

References:

1. Hunink M et al. Decision making is health and medicine. 2001 Cambridge University Press.
2. DATA Treeage tutorials - www.treeage.com
3. TreePlan tutorials - www.treeplan.com
4. Ebell MH, An introduction to information mastery - decision analyses - www.poems.msu.edu/infomastery.